Melissa Rauch

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

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

Sheldon's World of Warcraft online game account is hacked and he is determined to find out who did it. Also Penny shares some girl talk with her friends about Leonard and his new girlfriend.

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

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

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