Season 4
Episodes
S4 · E1 · 23 Sept 2010 · 21 min
The Robotic Manipulation
Penny tags along on Sheldon's first ever date; Wolowitz finds a new use for a robotic arm.
S4 · E2 · 30 Sept 2010 · 21 min
The Cruciferous Vegetable Amplification
Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.
S4 · E3 · 7 Oct 2010 · 21 min
The Zazzy Substitution
The guys are concerned as Sheldon searches for an alternative to human companionship.
S4 · E4 · 14 Oct 2010 · 20 min
The Hot Troll Deviation
An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.
S4 · E5 · 21 Oct 2010 · 21 min
The Desperation Emanation
Leonard realizes he’s the only one without a girlfriend, while Sheldon wants to get rid of his.
S4 · E6 · 28 Oct 2010 · 22 min
The Irish Pub Formulation
Leonard keeps an affair a secret from Sheldon, Howard and Raj.
S4 · E7 · 4 Nov 2010 · 21 min
The Apology Insufficiency
Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.
S4 · E8 · 11 Nov 2010 · 19 min
The 21-Second Excitation
While the guys camp in line for a long-awaited movie screening, Penny and Bernadette invite Amy to her first slumber party.
S4 · E9 · 18 Nov 2010 · 21 min
The Boyfriend Complexity
Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.
S4 · E10 · 9 Dec 2010 · 20 min
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.
S4 · E11 · 16 Dec 2010 · 20 min
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.
S4 · E12 · 6 Jan 2011 · 21 min
The Bus Pants Utilization
Leonard's idea for a smartphone app derails his friendship with Sheldon.
S4 · E13 · 20 Jan 2011 · 21 min
The Love Car Displacement
Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.
S4 · E14 · 3 Feb 2011 · 21 min
The Thespian Catalyst
Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about a friend's girlfriend.
S4 · E15 · 10 Feb 2011 · 20 min
The Benefactor Factor
A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.
S4 · E16 · 17 Feb 2011 · 20 min
The Cohabitation Formulation
As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.
S4 · E17 · 24 Feb 2011 · 21 min
The Toast Derivation
Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.
S4 · E18 · 10 Mar 2011 · 21 min
The Prestidigitation Approximation
Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continue being friends with Penny.
S4 · E19 · 31 Mar 2011 · 21 min
The Zarnecki Incursion
Sheldon's online-game account is hacked by Todd Zarnecki, who then proceeds to steal all his items prompting the guys to go on a quest to retrieve them. Penny, Bernadette and Amy discuss how Penny groomed Leonard to be willing to try various things and more adventurous boyfriend... for some other woman — Priya.
S4 · E20 · 7 Apr 2011 · 21 min
The Herb Garden Germination
Sheldon and Amy decide to start several rumors about the others as a test. Meanwhile, Howard takes his relationship with Bernadette to even higher level.
S4 · E21 · 28 Apr 2011 · 21 min
The Agreement Dissection
When Leonard spends too much time in the shower with Priya, Sheldon charges Leonard with two violations of the roommate agreement. However, before he can get too far, Priya uses her skills as a lawyer to nullify the charges due to the agreement's vague wording, much to Sheldon's dismay. When the guys take advantage of Priya's skills in order to eat Greek food on pizza night, Sheldon goes to Penny, who invites him to a girls' night out with Amy and Bernadette, which Sheldon agrees to after Penny mentions that they may be talking trash about Priya. After the girls drink some cocktails, they decide to take Sheldon dancing, which Sheldon reluctantly goes along with. After dancing, Sheldon takes an intoxicated Amy back to her apartment and as well as talking about Priya, meets a monkey who is addicted to smoking cigarettes. Amy tells Sheldon not to give in to Priya's law skills, before kissing him and going to her bathroom to vomit.
S4 · E22 · 5 May 2011 · 21 min
The Wildebeest Implementation
Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.
S4 · E23 · 12 May 2011 · 20 min
The Engagement Reaction
When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.
S4 · E24 · 19 May 2011 · 21 min
The Roommate Transmogrification
When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she's regrets.
Data and images from TMDB.