The Solder Excursion Diversion: Sheldon makes a surprise revelation when Amy buys him a new laptop. Leonard and Howard lie to their wives to avoid an errand. (S9 Ep19) [AD,S]
The Big Bear Precipitation: Sheldon shares a secret about Leonard when the two of them go on a weekend trip to a cabin in the country with Amy and Penny. (S9 Ep20) [AD,S]
The Viewing Party Combustion: During a get-together to watch TV at the flat, a minor argument between Sheldon and Leonard escalates into a heated debate. (S9 Ep21) [AD,S]
The Solder Excursion Diversion: Sheldon makes a surprise revelation when Amy buys him a new laptop. Leonard and Howard lie to their wives to avoid an errand. (S9 Ep19) [AD,S]
The Big Bear Precipitation: Sheldon shares a secret about Leonard when the two of them go on a weekend trip to a cabin in the country with Amy and Penny. (S9 Ep20) [AD,S]
The Viewing Party Combustion: During a get-together to watch TV at the flat, a minor argument between Sheldon and Leonard escalates into a heated debate. (S9 Ep21) [AD,S]
The Vegas Renormalization: Leonard and Raj take a heartbroken Howard to Las Vegas, leaving Sheldon locked out of his flat and forced to stay with Penny. (S2 Ep21) [AD,S]
The Classified Materials Turbulence: Things look up for Leonard when Penny makes a surprising revelation on her second date with Stuart. Howard sees a flaw in his NASA project. (S2 Ep22) [AD,S]
The Fuzzyboots Corollary: Leonard is upset when he discovers that Penny is seeing someone, so he plucks up the courage to ask a woman out on a date. (S1 Ep3) [AD,S]
The Fermentation Bifurcation: The gang run into Penny's ex-boyfriend, Zack, at a wine bar. Bernadette, who can't drink, hangs out with Sheldon. (S9 Ep22) [AD,S]
The Line Substitution Solution: Sheldon pays Stuart to spend the afternoon shopping with Amy so that he can queue up to see a special film screening instead. (S9 Ep23) [AD,S]
The Convergence Convergence: Conflict arises when Leonard's recently divorced parents and Sheldon's devoutly religious mother are all in town at the same time. (S9 Ep24) [AD,S]
The Fermentation Bifurcation: The gang run into Penny's ex-boyfriend, Zack, at a wine bar. Bernadette, who can't drink, hangs out with Sheldon. (S9 Ep22) [AD,S]
The Line Substitution Solution: Sheldon pays Stuart to spend the afternoon shopping with Amy so that he can queue up to see a special film screening instead. (S9 Ep23) [AD,S]
The Convergence Convergence: Conflict arises when Leonard's recently divorced parents and Sheldon's devoutly religious mother are all in town at the same time. (S9 Ep24) [AD,S]
The Romance Recalibration: Penny thinks that Leonard has stopped making an effort in their relationship, so she decides to go away for a spa weekend with Amy. (S10 Ep13) [AD,S]
The Emotion Detection Automation: Sheldon tests a new invention after hearing that it could help him to read people's emotions. Raj seeks dating advice. (S10 Ep14) [AD,S]
The Locomotion Reverberation: Leonard and Howard distract Sheldon with a trip to a historic railway when he slows their progress on the guidance system. (S10 Ep15) [AD,S]
The Romance Recalibration: Penny thinks that Leonard has stopped making an effort in their relationship, so she decides to go away for a spa weekend with Amy. (S10 Ep13) [AD,S]
The Emotion Detection Automation: Sheldon tests a new invention after hearing that it could help him to read people's emotions. Raj seeks dating advice. (S10 Ep14) [AD,S]
The Monopolar Expedition: Leonard and Penny reconsider their feelings for each other, but then Leonard is offered the opportunity to spend the summer working at the North Pole. (S2 Ep23) [AD,S]
The Locomotion Reverberation: Leonard and Howard distract Sheldon with a trip to a historic railway when he slows their progress on the guidance system. (S10 Ep15) [AD,S]
The Electric Can Opener Fluctuation: Leonard's attempts to woo Penny are constantly thwarted. Sheldon heads to Texas after learning his friends meddled with his expedition data. (S3 Ep1) [AD,S]
The Luminous Fish Effect: Getting fired forces Sheldon to ponder life outside physics, so Leonard has to take drastic action to snap his friend out of his reverie. (S1 Ep4) [AD,S]
The Hamburger Postulate: Leonard thinks he's been wasting his time on Penny, so he turns his attention to Leslie. Sheldon's uncomfortable with a change to his hamburger routine. (S1 Ep5) [AD,S]
The Luminous Fish Effect: Getting fired forces Sheldon to ponder life outside physics, so Leonard has to take drastic action to snap his friend out of his reverie. (S1 Ep4) [AD,S]
The Hamburger Postulate: Leonard thinks he's been wasting his time on Penny, so he turns his attention to Leslie. Sheldon's uncomfortable with a change to his hamburger routine. (S1 Ep5) [AD,S]
The Conjugal Conjecture: The gang face an awkward morning after Sheldon's mother and Leonard's father share an evening together. Penny's family arrive in town. (S10 Ep1) [AD,S]
The Military Miniaturization: Howard has a meeting with Air Force representative Colonel Williams about the gyroscope he invented with Leonard and Sheldon. (S10 Ep2) [AD,S]
The Dependence Transcendence: Tensions rise when the guys struggle to complete their Air Force project on time and are forced to work around the clock. (S10 Ep3) [AD,S]
The Conjugal Conjecture: The gang face an awkward morning after Sheldon's mother and Leonard's father share an evening together. Penny's family arrive in town. (S10 Ep1) [AD,S]
The Military Miniaturization: Howard has a meeting with Air Force representative Colonel Williams about the gyroscope he invented with Leonard and Sheldon. (S10 Ep2) [AD,S]
The Dependence Transcendence: Tensions rise when the guys struggle to complete their Air Force project on time and are forced to work around the clock. (S10 Ep3) [AD,S]
The Allowance Evaporation: Amy is furious when she learns that Sheldon has shared intimate details of their relationship with his colleagues. (S10 Ep16) [AD,S]
The Comic-Con Conundrum: Cut off from his father's fortune, Raj appoints Sheldon to organise his finances. Penny considers joining the guys at Comic-Con. (S10 Ep17) [AD,S]
The Escape Hatch Identification: Leonard and Penny offer Sheldon's old room to Raj when he's forced to move out of his flat, leading to unexpected conflict. (S10 Ep18) [AD,S]
The Allowance Evaporation: Amy is furious when she learns that Sheldon has shared intimate details of their relationship with his colleagues. (S10 Ep16) [AD,S]
The Comic-Con Conundrum: Cut off from his father's fortune, Raj appoints Sheldon to organise his finances. Penny considers joining the guys at Comic-Con. (S10 Ep17) [AD,S]
The Jiminy Conjecture: Leonard and Penny feel awkward around each other after their romantic liaison, while Sheldon and Howard take bets to determine a species of cricket. (S3 Ep2) [AD,S]
The Escape Hatch Identification: Leonard and Penny offer Sheldon's old room to Raj when he's forced to move out of his flat, leading to unexpected conflict. (S10 Ep18) [AD,S]
The Gothowitz Deviation: Sheldon tries to modify Penny's behaviour, and rewards her with chocolate when she does what he wants, while Howard and Raj go to a goth nightclub. (S3 Ep3) [AD,S]
The Middle Earth Paradigm: Penny's Halloween party puts Leonard, Sheldon, Howard and Raj through a demanding new test of their social skills. (S1 Ep6) [AD,S]
The Dumpling Paradox: When Howard seduces Penny's friend and spends the night with her in Penny's flat, Penny asks if she can sleep on Leonard and Sheldon's sofa. (S1 Ep7) [AD,S]
The Middle Earth Paradigm: Penny's Halloween party puts Leonard, Sheldon, Howard and Raj through a demanding new test of their social skills. (S1 Ep6) [AD,S]
The Dumpling Paradox: When Howard seduces Penny's friend and spends the night with her in Penny's flat, Penny asks if she can sleep on Leonard and Sheldon's sofa. (S1 Ep7) [AD,S]
The Cohabitation Experimentation: When Amy's flat is flooded, she has to move out while it is being repaired and proposes a 'cohabitation experiment' with Sheldon. (S10 Ep4) [AD,S]
The Hot Tub Contamination: Leonard and Penny intervene when Sheldon and Amy have an argument. Howard and Bernadette are disturbed by unexpected guests. (S10 Ep5) [AD,S]
The Fetal Kick Catalyst: Penny meets her fans at a comic book convention. Sheldon and Amy host brunch at Penny's flat. Howard makes an impulsive purchase. (S10 Ep6) [AD,S]
The Cohabitation Experimentation: When Amy's flat is flooded, she has to move out while it is being repaired and proposes a 'cohabitation experiment' with Sheldon. (S10 Ep4) [AD,S]
The Hot Tub Contamination: Leonard and Penny intervene when Sheldon and Amy have an argument. Howard and Bernadette are disturbed by unexpected guests. (S10 Ep5) [AD,S]
The Fetal Kick Catalyst: Penny meets her fans at a comic book convention. Sheldon and Amy host brunch at Penny's flat. Howard makes an impulsive purchase. (S10 Ep6) [AD,S]
The Collaboration Fluctuation: Leonard, Penny and Raj settle into their new living arrangement, and Sheldon expresses an interest in Amy's professional life. (S10 Ep19) [AD,S]
The Recollection Dissipation: Sheldon collaborates on two projects - one with Leonard and Howard, plus another with Amy - pushing himself to the limit. (S10 Ep20) [AD,S]
The Separation Agitation: Howard and Bernadette are upset when they leave Halley at the nursery. Bert the geologist introduces his girlfriend to the gang. (S10 Ep21/24) [AD,S]
The Collaboration Fluctuation: Leonard, Penny and Raj settle into their new living arrangement, and Sheldon expresses an interest in Amy's professional life. (S10 Ep19) [AD,S]
The Recollection Dissipation: Sheldon collaborates on two projects - one with Leonard and Howard, plus another with Amy - pushing himself to the limit. (S10 Ep20) [AD,S]
The Pirate Solution: Raj must find a job or he'll be sent back to India, so he accepts an offer of work from Sheldon. Leonard and Penny try to get some time for themselves. (S3 Ep4) [AD,S]
The Separation Agitation: Howard and Bernadette are upset when they leave Halley at the nursery. Bert the geologist introduces his girlfriend to the gang. (S10 Ep21/24) [AD,S]
The Creepy Candy Coating Corollary: Due to a childhood snub, Sheldon is irked when Star Trek actor Wil Wheaton (guest starring as himself) takes part in the same contest as him. (S3 Ep5) [AD,S]
The Grasshopper Experiment: Raj panics when his parents arrange a blind date for him. But he discovers that he can talk to her - after a few drinks. (S1 Ep8) [AD,S]
The Cooper-Hofstadter Polarization: Sheldon and Leonard fall out when they're asked to collaborate at a physics conference. Penny tries to help but just makes things worse. (S1 Ep9) [AD,S]
The Grasshopper Experiment: Raj panics when his parents arrange a blind date for him. But he discovers that he can talk to her - after a few drinks. (S1 Ep8) [AD,S]
The Cooper-Hofstadter Polarization: Sheldon and Leonard fall out when they're asked to collaborate at a physics conference. Penny tries to help but just makes things worse. (S1 Ep9) [AD,S]
The Veracity Elasticity: Leonard is upset when he finds out that Penny has been moving his collectables out of Sheldon's old room and into storage behind his back. (S10 Ep7) [AD,S]
The Brain Bowl Incubation: Sheldon tries to convince Amy that they should procreate. Raj feels embarrassed about what the new woman in his life does for a living. (S10 Ep8) [AD,S]
The Geology Elevation: Sheldon can't contain his jealousy when he hears that his university colleague, Bert the geologist, has won a prestigious fellowship. (S10 Ep9) [AD,S]
The Veracity Elasticity: Leonard is upset when he finds out that Penny has been moving his collectables out of Sheldon's old room and into storage behind his back. (S10 Ep7) [AD,S]
The Brain Bowl Incubation: Sheldon tries to convince Amy that they should procreate. Raj feels embarrassed about what the new woman in his life does for a living. (S10 Ep8) [AD,S]
The Geology Elevation: Sheldon can't contain his jealousy when he hears that his university colleague, Bert the geologist, has won a prestigious fellowship. (S10 Ep9) [AD,S]
The Cognition Regeneration: Leonard isn't happy when he finds out that Penny is considering accepting a job offer from her ex-boyfriend Zack. (S10 Ep22/24) [AD,S]
The Gyroscopic Collapse: Amy is offered a fellowship at Princeton, Raj makes new living arrangements, and the guys' gyroscope project spins out of control. (S10 Ep23/24) [AD,S]
The Long Distance Dissonance: The gang worry when Sheldon's former admirer, Dr Ramona Nowitzki, turns up while Amy is away working at Princeton. (S10 Ep24/24) [AD,S]
The Cognition Regeneration: Leonard isn't happy when he finds out that Penny is considering accepting a job offer from her ex-boyfriend Zack. (S10 Ep22/24) [AD,S]
The Gyroscopic Collapse: Amy is offered a fellowship at Princeton, Raj makes new living arrangements, and the guys' gyroscope project spins out of control. (S10 Ep23/24) [AD,S]
The Cornhusker Vortex: Sheldon teaches Leonard about American football so that he can try to fit in with Penny's friends. And Raj and Sheldon have a kite-fighting contest. (S3 Ep6) [AD,S]
The Long Distance Dissonance: The gang worry when Sheldon's former admirer, Dr Ramona Nowitzki, turns up while Amy is away working at Princeton. (S10 Ep24/24) [AD,S]
The Guitarist Amplification: Sheldon is annoyed when Leonard and Penny argue about Penny's male friend staying over and he has to act as peacemaker. (S3 Ep7) [AD,S]
The Loobenfeld Decay: Leonard and Sheldon each tell a lie to avoid going to see Penny singing on stage in a production of Rent, but Sheldon's fib gets out of control. (S1 Ep10) [AD,S]
The Pancake Batter Anomaly: Penny volunteers to nurse Sheldon when he's sick. But his friends, who know how miserable he is when he's ill, stay well away. (S1 Ep11) [AD,S]
The Work Song Nanocluster: Penny's home-based business selling hair accessories gets out of hand when an overexcited Sheldon takes charge of production. (S2 Ep18) [AD,S]
The Terminator Decoupling: Leonard, Sheldon, Howard and Raj discover that beautiful sci-fi actress Summer Glau is on board their train to San Francisco. (S2 Ep17) [AD,S]
The Cushion Saturation: A game of paintball leads to a squabble when Penny accidentally shoots paint at one of Sheldon's cushions. Romance blossoms between Howard and Leslie. (S2 Ep16) [AD,S]
The Maternal Capacitance: A disastrous visit from Leonard's mother, Beverly, has the unexpected side-effect of bringing Leonard and Penny closer together. (S2 Ep15) [AD,S]
The Financial Permeability: When Sheldon lends Penny some money, it brings her ex-boyfriend Kurt back into her life, with negative consequences for the gang. (S2 Ep14) [AD,S]
The Friendship Algorithm: Sheldon develops a scientific procedure for making friends when he discovers that Kripke has control of a new supercomputer at the university. (S2 Ep13) [AD,S]
The Killer Robot Instability: Kripke challenges the boys to a robot duel, while Howard is devastated when Penny finally tells him what she thinks of his chauvinism. (S2 Ep12) [AD,S]
The Bath Item Gift Hypothesis: At Christmas, Leonard's hunky colleague starts dating Penny, while Sheldon's obsession with gift-giving etiquette torments everyone. (S2 Ep11) [AD,S]
The Vartabedian Conundrum: Leonard goes to Penny for help when his relationship with Stephanie takes off faster than he'd like, but will he act on her advice? (S2 Ep10) [AD,S]
The White Asparagus Triangulation: Sheldon is delighted that Leonard has finally found a girlfriend who matches up to his high standards... Perhaps a little too delighted. (S2 Ep9) [AD,S]
The Lizard-Spock Expansion: Howard is furious when a woman who he likes falls for Leonard instead, despite Howard's efforts to woo her. (S2 Ep8) [AD,S]
The Panty PiÄnata Polarization: Sheldon bans Penny from the flat for numerous minor infractions, so she retaliates. Howard and Raj search for the America's Next Top Model house. (S2 Ep7) [AD,S]
The Cooper-Nowitzki Theorem: Sheldon's friends are mystified when a younger student is attracted to him, but her intense devotion soon becomes too much to bear. (S2 Ep6) [AD,S]
The Euclid Alternative: When Leonard can't drive Sheldon to and from work, the friends stage an intervention to overcome Sheldon's fear of getting behind the wheel. (S2 Ep5) [AD,S]
The Griffin Equivalency: Full of confidence after being named one of People magazine's '30 to Watch Under 30', Raj hits on Penny and becomes impossibly arrogant. (S2 Ep4) [AD,S]
The Barbarian Sublimation: Penny becomes addicted to an online game based on the world of Conan the Barbarian and begins to pester Sheldon for advice. (S2 Ep3) [AD,S]
The Codpiece Topology: Seeing Penny out on a date with another guy sends a distressed Leonard rushing back to Leslie Winkle, much to Sheldon's dismay. (S2 Ep2) [AD,S]
The Bad Fish Paradigm: Penny opens up to a reluctant Sheldon after a less-than-stellar first date with Leonard, putting him in the awkward position of having to keep a secret. (S2 Ep1) [AD,S]
The Vartabedian Conundrum: Leonard goes to Penny for help when his relationship with Stephanie takes off faster than he'd like, but will he act on her advice? (S2 Ep10) [AD,S]
The White Asparagus Triangulation: Sheldon is delighted that Leonard has finally found a girlfriend who matches up to his high standards... Perhaps a little too delighted. (S2 Ep9) [AD,S]
The Lizard-Spock Expansion: Howard is furious when a woman who he likes falls for Leonard instead, despite Howard's efforts to woo her. (S2 Ep8) [AD,S]
The Panty PiÄnata Polarization: Sheldon bans Penny from the flat for numerous minor infractions, so she retaliates. Howard and Raj search for the America's Next Top Model house. (S2 Ep7) [AD,S]
The Cooper-Nowitzki Theorem: Sheldon's friends are mystified when a younger student is attracted to him, but her intense devotion soon becomes too much to bear. (S2 Ep6) [AD,S]
The Euclid Alternative: When Leonard can't drive Sheldon to and from work, the friends stage an intervention to overcome Sheldon's fear of getting behind the wheel. (S2 Ep5) [AD,S]
The Griffin Equivalency: Full of confidence after being named one of People magazine's '30 to Watch Under 30', Raj hits on Penny and becomes impossibly arrogant. (S2 Ep4) [AD,S]
The Barbarian Sublimation: Penny becomes addicted to an online game based on the world of Conan the Barbarian and begins to pester Sheldon for advice. (S2 Ep3) [AD,S]
The Codpiece Topology: Seeing Penny out on a date with another guy sends a distressed Leonard rushing back to Leslie Winkle, much to Sheldon's dismay. (S2 Ep2) [AD,S]
The Bad Fish Paradigm: Penny opens up to a reluctant Sheldon after a less-than-stellar first date with Leonard, putting him in the awkward position of having to keep a secret. (S2 Ep1) [AD,S]
The Pancake Batter Anomaly: Penny volunteers to nurse Sheldon when he's sick. But his friends, who know how miserable he is when he's ill, stay well away. (S1 Ep11) [AD,S]
The Loobenfeld Decay: Leonard and Sheldon each tell a lie to avoid going to see Penny singing on stage in a production of Rent, but Sheldon's fib gets out of control. (S1 Ep10) [AD,S]
The Cooper-Hofstadter Polarization: Sheldon and Leonard fall out when they're asked to collaborate at a physics conference. Penny tries to help but just makes things worse. (S1 Ep9) [AD,S]
The Grasshopper Experiment: Raj panics when his parents arrange a blind date for him. But he discovers that he can talk to her - after a few drinks. (S1 Ep8) [AD,S]
Pilot: The first ever episode of the hit sitcom. Leonard and Sheldon's geeky world is shaken up by the arrival of a beautiful new neighbour. (S1 Ep1) [AD,S]
The Stockholm Syndrome: Howard and Bernadette go on a trip without their children, Leonard and Penny try to keep a secret, and Raj makes a new friend. (S12 Ep24) [AD,S]
The Change Constant: Sheldon and Amy stay up late awaiting a phone call that could bring big news from the Nobel Committee: are their lives about to change? (S12 Ep23) [AD,S]
The Maternal Conclusion: Leonard is surprised when his mother Beverly comes to visit and is kind to him, until he finds out the real reason she's there. (S12 Ep22) [AD,S]
The Dumpling Paradox: When Howard seduces Penny's friend and spends the night with her in Penny's flat, Penny asks if she can sleep on Leonard and Sheldon's sofa. (S1 Ep7) [AD,S]
The Middle Earth Paradigm: Penny's Halloween party puts Leonard, Sheldon, Howard and Raj through a demanding new test of their social skills. (S1 Ep6) [AD,S]
The Hamburger Postulate: Leonard thinks he's been wasting his time on Penny, so he turns his attention to Leslie. Sheldon's uncomfortable with a change to his hamburger routine. (S1 Ep5) [AD,S]
The Luminous Fish Effect: Getting fired forces Sheldon to ponder life outside physics, so Leonard has to take drastic action to snap his friend out of his reverie. (S1 Ep4) [AD,S]
The Fuzzyboots Corollary: Leonard is upset when he discovers that Penny is seeing someone, so he plucks up the courage to ask a woman out on a date. (S1 Ep3) [AD,S]
Pilot: The first ever episode of the hit sitcom. Leonard and Sheldon's geeky world is shaken up by the arrival of a beautiful new neighbour. (S1 Ep1) [AD,S]
The Stockholm Syndrome: Howard and Bernadette go on a trip without their children, Leonard and Penny try to keep a secret, and Raj makes a new friend. (S12 Ep24) [AD,S]
The Change Constant: Sheldon and Amy stay up late awaiting a phone call that could bring big news from the Nobel Committee: are their lives about to change? (S12 Ep23) [AD,S]
The Maternal Conclusion: Leonard is surprised when his mother Beverly comes to visit and is kind to him, until he finds out the real reason she's there. (S12 Ep22) [AD,S]
The Plagiarism Schism: Barry Kripke finds proof that Dr Pemberton plagiarised his thesis in college. Should Sheldon and Amy turn in their rival? (S12 Ep21) [AD,S]
The Decision Reverberation: Raj publishes a paper that suggests he may have discovered alien life. Penny encourages Leonard to stand up for himself. (S12 Ep20) [AD,S]
The Inspiration Deprivation: Amy has a meltdown when she feels the pressure of what it would mean for women everywhere if she were to win a Nobel Prize. (S12 Ep19) [AD,S]
The Laureate Accumulation: When their academic competitors charm America on a publicity tour, Sheldon and Amy try to get some Nobel laureates on their side. (S12 Ep18) [AD,S]