The Big Bang Theory
Season 4
24 episodes
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S04E01 The Robotic Manipulation
Penny finds herself along for the ride on Sheldon's first date ever; while Wolowitz finds a new use for a robotic arm.
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S04E02 The Cruciferous Vegetable Amplification
Sheldon realizes he won't live long enough to download his consciousness into a robot body, and attempts to extend his lifespan.
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S04E03 The Zazzy Substitution
The guys are concerned as Sheldon searches for an alternative to human companionship.
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S04E04 The Hot Troll Deviation
An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.
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S04E05 The Desperation Emanation
Leonard realizes he's the only one without a girlfriend, while Sheldon wants to get rid of his.
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S04E06 The Irish Pub Formulation
Leonard keeps an affair secret from Sheldon, Howard and Raj.
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S04E07 The Apology Insufficiency
Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.
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S04E08 The 21-Second Excitation
While the guys camp in line for a screening, Penny and Bernadette invite Amy to her first slumber party.
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S04E09 The Boyfriend Complexity
Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.
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S04E10 The Alien Parasite Hypothesis
Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.
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S04E11 The Justice League Recombination
The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.
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S04E12 The Bus Pants Utilization
Leonard's idea for a smartphone app derails his friendship with Sheldon.
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S04E13 The Love Car Displacement
Tension runs high when everyone is staying at the same hotel for a science event and Bernadette runs into her ex-boyfriend.
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S04E14 The Thespian Catalyst
Sheldon hopes acting lessons from Penny will help him become a better teacher. Meanwhile, Koothrappali fantasizes about his best friend's girlfriend.
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S04E15 The Benefactor Factor
A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.
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S04E16 The Cohabitation Formulation
As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.
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S04E17 The Toast Derivation
Sheldon struggles to cope when he realizes it's actually Leonard who is the center of their social group.
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S04E18 The Prestidigitation Approximation
Leonard must choose between new girlfriend Priya and his friendship with Penny. Meanwhile, Howard drives Sheldon crazy with a magic trick.
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S04E19 The Zarnecki Incursion
When someone hacks Sheldon's online game account, the guys go on a quest to find the culprit.
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S04E20 The Herb Garden Germination
Sheldon and Amy experiment on their friends by spreading gossip, while Howard takes a big step in his relationship with Bernadette.
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S04E21 The Agreement Dissection
When Priya uses her lawyer skills to pick apart the roommate agreement, the girls take Sheldon dancing.
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S04E22 The Wildebeest Implementation
Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.
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S04E23 The Engagement Reaction
When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.
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S04E24 The Roommate Transmogrification
When Bernadette receives her Ph.D., the guys take joy in reminding an emasculated Wolowitz that he is the only one in their group who isn't a doctor. Meanwhile, Koothrappali becomes Sheldon's new roommate after hearing Leonard and Priya engaging in a "Star Trek" bedroom fantasy.
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