As Howard and his fellow astronauts sit in the space shuttle awaiting launch, he reflects on...

Howard tries to use his wedding as an excuse to avoid being sent into space, but ends up...

Leonard, Sheldon and Raj organise a stag party for Howard, but stories about his sexual history...

Howard is put in charge of looking after Stephen Hawking's wheelchair when the famous scientist...

Penny buys Leonard and Sheldon some Star Trek action figures, but the duo refuse to remove them...

Amy is disappointed with Sheldon when he announces he is breaking his promise to go with her to...

Sheldon refuses to get his hair cut after his regular barber dies - a solitary change that...

Leonard, Raj and Howard devise a contest to decide whether Sheldon or Kripke should get...

Sheldon uses his holidays to help Amy in her biology lab, but moans about the menial jobs he is...

After a sleepless night, Leonard breaks his room-mate agreement with Sheldon. Howard makes...

Leonard and Penny continue testing their rekindled relationship using an innovative system to...

Leonard asks Penny out on a date, and they agree to give their relationship another chance....

Comedy about four friends who understand more about the laws of physics than they do about...

Sheldon is uninterested in Amy's career, so Penny, Raj and Leonard try to make him understand...

Leonard confronts the man who tormented him in high school, while Penny realises she did her...

Comic-book store owner Stuart asks Amy out on a date, forcing a jealous Sheldon to consider the...

Leonard and Penny endure an awkward night at the cinema, both insisting the outing is not a...

Amy is hurt to discover Penny and Bernadette went shopping for bridesmaid dresses without her....

Leonard has doubts about his feelings for Priya when he kisses a girl he meets in the...

Sheldon's mother comes to visit and woos the gang, but he cannot help feeling jealous of all...

Sheldon's old adversary Wil Wheaton returns and invites everyone to a housewarming party....

Raj feels upset about not being in a relationship, so Penny sets out to find a date and...

Leonard inadvertently gives the impression he is attracted to Amy when he accompanies her to a...

Amy is caught in a battle of wills between Sheldon and Penny, while Leonard tries to reignite...

Penny worries about the consequences of spending the night with Raj, and Leonard's reaction...