Season: 5

Penny buys Leonard and Sheldon “Star Trek” collectibles as a thank-you, leading Sheldon to be haunted by Mr. Spock. Meanwhile, Raj decides he has met the “Future Mrs. Koothrappali” after his parents set him up on a date.

Sheldon must choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys.

A fight between Sheldon and Penny leaves Amy caught in the middle. Meanwhile, Leonard tries to spice up his long-distance relationship with Priya.

Sheldon becomes agitated when his regular barber is out sick. Astronaut training causes Howard to reconsider wanting to go into space. Penny beats Leonard in chess, the first time she plays.

Penny is worried with how damaged her friendship with the guys will be in the aftermath of her sleeping with Raj, while Sheldon becomes the leader of the paintball team.

Sheldon and his rival Barry Kripke fight it out over the availability of a new office. Penny gets a gift from Amy that really tests their friendship and it doesn't end well.

Sheldon gets in trouble with Amy when he isn't impressed by her recent accomplishment, and Howard must come to grips with Bernadette's dislike of children.

When Sheldon is forced to take his vacation, he goes to work with Amy in her neurobiology lab. Also, Bernadette wants Howard to sign a pre-nup.

When Leonard's former high school tormentor resurfaces, Leonard must confront him. Meanwhile, Penny realizes she did her fair share of tormenting in the past.

Sheldon's selfish demands force Leonard to reconsider their friendship. Meanwhile, Wolowitz tries to pick his astronaut nickname.