The Best Episodes of The Big Bang Theory Season 4

Penny tags along on Sheldon's first ever date; Wolowitz finds a new use for a robotic arm.

Director: Mark Cendrowski

Writer: N/A

The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.

Director: Mark Cendrowski

Writer: N/A

When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she's regrets.

Director: Mark Cendrowski

Writer: N/A

Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.

Director: Mark Cendrowski

Writer: N/A

Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.

Director: Mark Cendrowski

Writer: N/A

Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.

Director: Anthony Joseph Rich

Writer: N/A

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.

Director: Mark Cendrowski

Writer: N/A

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.

Director: Mark Cendrowski

Writer: N/A

While the guys camp in line for a long-awaited movie screening, Penny and Bernadette invite Amy to her first slumber party.

Director: Mark Cendrowski

Writer: N/A

Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continue being friends with Penny.

Director: Mark Cendrowski

Writer: N/A

An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.

Director: Mark Cendrowski

Writer: N/A

Leonard keeps an affair a secret from Sheldon, Howard and Raj.

Director: Mark Cendrowski

Writer: N/A

Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.

Director: Mark Cendrowski

Writer: N/A

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.

Director: Peter Chakos

Writer: N/A

When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.

Director: Howard Murray

Writer: N/A

The guys are concerned as Sheldon searches for an alternative to human companionship.

Director: Mark Cendrowski

Writer: N/A

Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.

Director: Mark Cendrowski

Writer: N/A

As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.

Director: Mark Cendrowski

Writer: N/A

Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about a friend's girlfriend.

Director: Mark Cendrowski

Writer: N/A

A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.

Director: Mark Cendrowski

Writer: N/A

Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.

Director: Mark Cendrowski

Writer: N/A

Leonard realizes he’s the only one without a girlfriend, while Sheldon wants to get rid of his.

Director: Mark Cendrowski

Writer: N/A

Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.

Director: Mark Cendrowski

Writer: N/A

Leonard's idea for a smartphone app derails his friendship with Sheldon.

Director: Mark Cendrowski

Writer: N/A