Melissa Rauch

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

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.

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

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

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