The Plimpton Stimulation: When Sheldon meets a famous physicist online, he invites her over to the apartment, where she spends her time flirting with Leonard. (S3 Ep21) [AD,S]
The Citation Negation: Sheldon and Amy get some devastating news. Bernadette asks Stuart's girlfriend Denise to teach her how to beat Howard at a video game. (S12 Ep9) [AD,S]
The VCR Illumination: Sheldon and Amy are still upset about their theory being disproven, but a video tape from Sheldon's past inspires him not to give up. (S12 Ep10) [AD,S]
The Paintball Scattering: Jealousy, trust issues and tension among the couples in the gang cause mayhem when Penny and Leonard organise a paintball game. (S12 Ep11) [AD,S]
The Propagation Proposition: Penny's ex-boyfriend Zack and his wife want a baby, but when they encounter fertility problems, they ask Leonard for his help. (S12 Ep12) [AD,S]
The Confirmation Polarization: Sheldon and Amy are thrilled when their super-asymmetry theory is proved correct. Bernadette enjoys some big success at work. (S12 Ep13) [AD,S]
The Meteorite Manifestation: Sheldon is thrilled to help Howard and Bernadette with some bureaucratic paperwork, until he realises that they're breaking the law. (S12 Ep14) [AD,S]
The Conference Valuation: Penny and Bernadette go to San Diego for a sales convention, leaving Howard in charge of Michael and Halley while they're away. (S12 Ep17) [AD,S]
The Donation Oscillation: Penny attempts to sabotage Leonard's efforts to help her ex-boyfriend Zack and his wife Marissa have a family of their own. (S12 Ep15) [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]
The D & D Vortex: When the gang find out that Wil Wheaton is hosting a celebrity game of Dungeons & Dragons at his home, deception and betrayal take hold. (S12 Ep16) [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 Conference Valuation: Penny and Bernadette go to San Diego for a sales convention, leaving Howard in charge of Michael and Halley while they're away. (S12 Ep17) [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 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]
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 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 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 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 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 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 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 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 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 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 21-Second Excitation: The gang's plans to attend a film screening are scuppered by Sheldon's nemesis Wil Wheaton. Penny and Bernadette invite Amy to her first slumber party. (S4 Ep8) [AD,S]
The Boyfriend Complexity: When Penny's father visits, Leonard discovers that her parents still think that he and Penny are a couple, so he takes advantage of the situation. (S4 Ep9) [AD,S]
The Conjugal Configuration: Sheldon and Amy's honeymoon runs aground, while Penny and Leonard discover that they are uncomfortably similar to Amy's parents. (S12 Ep1) [AD,S]
The Wedding Gift Wormhole: A stressed Sheldon and Amy struggle to work out what the 'perfect gift' is that Leonard and Penny gave them on their wedding day. (S12 Ep2) [AD,S]
The Conjugal Configuration: Sheldon and Amy's honeymoon runs aground, while Penny and Leonard discover that they are uncomfortably similar to Amy's parents. (S12 Ep1) [AD,S]
The Wedding Gift Wormhole: A stressed Sheldon and Amy struggle to work out what the 'perfect gift' is that Leonard and Penny gave them on their wedding day. (S12 Ep2) [AD,S]
The Thanksgiving Decoupling: Howard takes the gang to his mother's house for Thanksgiving to protect himself from his grumpy father-in-law who has also been invited. (S7 Ep9) [AD,S]
The Discovery Dissipation: Sheldon feels guilty when he gets attention for his accidental discovery of a new element. Raj stays with Howard and Bernadette for a week. (S7 Ep10) [AD,S]
The Cooper Extraction: Sheldon has to go back to Texas when his sister goes into labour. While he's away, the gang gather at the flat to decorate the Christmas tree. (S7 Ep11) [AD,S]
The Thanksgiving Decoupling: Howard takes the gang to his mother's house for Thanksgiving to protect himself from his grumpy father-in-law who has also been invited. (S7 Ep9) [AD,S]
The Hesitation Ramification: Penny's big TV acting break hits the cutting-room floor, so Leonard does his best to comfort her, which leads her to ask him a bold question. (S7 Ep12) [AD,S]
The Discovery Dissipation: Sheldon feels guilty when he gets attention for his accidental discovery of a new element. Raj stays with Howard and Bernadette for a week. (S7 Ep10) [AD,S]
The Cooper Extraction: Sheldon has to go back to Texas when his sister goes into labour. While he's away, the gang gather at the flat to decorate the Christmas tree. (S7 Ep11) [AD,S]
The Hesitation Ramification: Penny's big TV acting break hits the cutting-room floor, so Leonard does his best to comfort her, which leads her to ask him a bold question. (S7 Ep12) [AD,S]
The Sales Call Sublimation: Penny gets more than she bargained for when Leonard meets a psychiatrist, while Sheldon and Raj make an astronomical discovery. (S9 Ep12) [AD,S]
The Empathy Optimization: The gang plan a Sheldon-free weekend in Las Vegas after coping with his constant demands, rudeness and ingratitude when he was ill. (S9 Ep13) [AD,S]
The Meemaw Materialization: Sheldon is thrilled when his beloved grandma 'Meemaw' comes to visit, but his excitement fades when she butts heads with Amy. (S9 Ep14) [AD,S]
The Sales Call Sublimation: Penny gets more than she bargained for when Leonard meets a psychiatrist, while Sheldon and Raj make an astronomical discovery. (S9 Ep12) [AD,S]
The Valentino Submergence: Sheldon and Amy host a special live Valentine's Day episode of their internet show Fun with Flags. Leonard and Penny grapple with getting older. (S9 Ep15) [AD,S]
The Empathy Optimization: The gang plan a Sheldon-free weekend in Las Vegas after coping with his constant demands, rudeness and ingratitude when he was ill. (S9 Ep13) [AD,S]
The Positive Negative Reaction: When Bernadette makes a big announcement, Howard becomes convinced that he needs to start earning more money. (S9 Ep16) [AD,S]
The Meemaw Materialization: Sheldon is thrilled when his beloved grandma 'Meemaw' comes to visit, but his excitement fades when she butts heads with Amy. (S9 Ep14) [AD,S]
The Celebration Experimentation: The gang persuade Sheldon to celebrate his birthday and invite a few special guests along to his party, in the 200th episode. (S9 Ep17) [AD,S]
The Valentino Submergence: Sheldon and Amy host a special live Valentine's Day episode of their internet show Fun with Flags. Leonard and Penny grapple with getting older. (S9 Ep15) [AD,S]
The Application Deterioration: Leonard, Sheldon and Howard run into problems when they file for a patent. Emily reaches out to Raj after their break-up. (S9 Ep18) [AD,S]
The Positive Negative Reaction: When Bernadette makes a big announcement, Howard becomes convinced that he needs to start earning more money. (S9 Ep16) [AD,S]
The Celebration Experimentation: The gang persuade Sheldon to celebrate his birthday and invite a few special guests along to his party, in the 200th episode. (S9 Ep17) [AD,S]
The Application Deterioration: Leonard, Sheldon and Howard run into problems when they file for a patent. Emily reaches out to Raj after their break-up. (S9 Ep18) [AD,S]
The Lunar Excitation: Raj registers Sheldon for online dating and finds the perfect match: the female version of Sheldon. Penny seduces Leonard while she's drunk. (S3 Ep23) [AD,S]
The Robotic Manipulation: Penny tags along to Sheldon's first date with a woman he's been texting for months. Howard finds a new use for a robotic arm. (S4 Ep1) [AD,S]
The Cruciferous Vegetable Amplification: Sheldon realises that he won't live long enough to download his consciousness into a robot body, so he tries to extend his lifespan. (S4 Ep2) [AD,S]
The Zazzy Substitution: The guys are concerned when a heartbroken Sheldon starts bulk buying cats after he breaks up with Amy, so Leonard tries to get Sheldon's mother to visit. (S4 Ep3) [AD,S]
The Hot Troll Deviation: An embarrassing secret of Howard's comes to light as he tries to win back Bernadette. Sheldon and Raj have trouble working together. (S4 Ep4) [AD,S]
The Desperation Emanation: Leonard realises he's the only one of the gang with no girlfriend. Sheldon wants to get rid of his when she hatches a plan for him to meet her mother. (S4 Ep5) [AD,S]
The Irish Pub Formulation: A visit from Raj's sister Priya creates tension among the guys, especially when Leonard asks Sheldon to conceal his romantic past with her. (S4 Ep6) [AD,S]
The Apology Insufficiency: Leonard thinks his dating problems are due to a lack of confidence, and vows to be self-assured around attractive women. Howard is called by the FBI. (S4 Ep7) [AD,S]
The 21-Second Excitation: The gang's plans to attend a film screening are scuppered by Sheldon's nemesis Wil Wheaton. Penny and Bernadette invite Amy to her first slumber party. (S4 Ep8) [AD,S]
The Boyfriend Complexity: When Penny's father visits, Leonard discovers that her parents still think that he and Penny are a couple, so he takes advantage of the situation. (S4 Ep9) [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]
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]
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 Bitcoin Entanglement: Sheldon seeks revenge when the guys cut him out of a potentially valuable investment. A secret about Leonard and Penny is revealed. (S11 Ep9) [AD,S]
The Celebration Reverberation: Sheldon and Howard plan birthday celebrations for Amy and Halley. Leonard is stressed by a Christmas letter from his brother. (S11 Ep11) [AD,S]
The Bitcoin Entanglement: Sheldon seeks revenge when the guys cut him out of a potentially valuable investment. A secret about Leonard and Penny is revealed. (S11 Ep9) [AD,S]
The Matrimonial Metric: Sheldon and Amy secretly test their friends, to work out who should be best man and maid of honour at their wedding. (S11 Ep12) [AD,S]
The Celebration Reverberation: Sheldon and Howard plan birthday celebrations for Amy and Halley. Leonard is stressed by a Christmas letter from his brother. (S11 Ep11) [AD,S]
The Matrimonial Metric: Sheldon and Amy secretly test their friends, to work out who should be best man and maid of honour at their wedding. (S11 Ep12) [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 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 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 Robotic Manipulation: Penny tags along to Sheldon's first date with a woman he's been texting for months. Howard finds a new use for a robotic arm. (S4 Ep1) [AD,S]
The Lunar Excitation: Raj registers Sheldon for online dating and finds the perfect match: the female version of Sheldon. Penny seduces Leonard while she's drunk. (S3 Ep23) [AD,S]
The Einstein Approximation: Sheldon is baffled by a formula he's working on, so he gets a less mentally taxing job at the Cheesecake Factory to kick-start his creativity. (S3 Ep14) [AD,S]
The Bozeman Reaction: After Leonard and Sheldon's flat is burgled, the gang create a new state-of-the-art security system to outwit any thieves and protect the place. (S3 Ep13) [AD,S]
The Psychic Vortex: Sheldon and Raj go to a university party where Raj lusts after a girl called Abby. Leonard regrets telling Penny that he disapproves of her belief in psychics. (S3 Ep12) [AD,S]
The Maternal Congruence: Leonard is horrified when his mother turns up unannounced for a Christmas visit, and then he finds out that Sheldon knew about her divorce before him. (S3 Ep11) [AD,S]
The Adhesive Duck Deficiency: Leonard, Raj and Howard go on a camping trip that alters their minds. Penny dislocates her shoulder when she slips in the shower. (S3 Ep8) [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 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 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 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 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 Plimpton Stimulation: When Sheldon meets a famous physicist online, he invites her over to the apartment, where she spends her time flirting with Leonard. (S3 Ep21) [AD,S]
The Spaghetti Catalyst: Sheldon hides his friendship with Penny from Leonard, but it isn't long before his double life is exposed. Can he remain friends with both of them? (S3 Ep20) [AD,S]
The Wheaton Recurrence: Leonard tells Penny that he loves her. The gang go bowling and find that Sheldon's enemy, Wil Wheaton, is playing in the opposing team. (S3 Ep19) [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 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 Excelsior Acquisition: Sheldon is summoned to court for driving through a red light. He misses the chance to meet Stan Lee and riles the judge. Will he go to prison? (S3 Ep16) [AD,S]
The Large Hadron Collision: Sheldon is gutted when Leonard asks Penny to go to Switzerland on Valentine's Day to see the world's largest particle accelerator instead of him. (S3 Ep15) [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 Einstein Approximation: Sheldon is baffled by a formula he's working on, so he gets a less mentally taxing job at the Cheesecake Factory to kick-start his creativity. (S3 Ep14) [AD,S]
The Psychic Vortex: Sheldon and Raj go to a university party where Raj lusts after a girl called Abby. Leonard regrets telling Penny that he disapproves of her belief in psychics. (S3 Ep12) [AD,S]
The Maternal Congruence: Leonard is horrified when his mother turns up unannounced for a Christmas visit, and then he finds out that Sheldon knew about her divorce before him. (S3 Ep11) [AD,S]
The Hofstadter Isotope: Leonard is devastated when Stuart from the comic book shop chats up Penny. Even worse, she doesn't mind. Sheldon tries to scupper the budding romance. (S2 Ep20) [AD,S]
The Dead Hooker Juxtaposition: Penny develops a rivalry with a sexy female neighbour who moves into the apartment building and threatens to become the 'new Penny'. (S2 Ep19) [AD,S]
The Adhesive Duck Deficiency: Leonard, Raj and Howard go on a camping trip that alters their minds. Penny dislocates her shoulder when she slips in the shower. (S3 Ep8) [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 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 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 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 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 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 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 has the unexpected side-effect of bringing Leonard and Penny closer together. (S2 Ep15) [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 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 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 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 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 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]