The Desperation Emanation
The Big Bang Theory Season 4 Episode 5 (10/21/10)
Amy wants to introduce Sheldon to her mother this week. When Sheldon hears the news he freaks out and tries to break all contact with her and avoid her. When she stalks him outside his apartment, he finds out she merely wanted to fake their relationship to keep her mother happy. He agrees and they do a web chat together with her.
Meanwhile, Leonard is feeling depressed when the rest of the gang has girlfriends and invokes the girlfriend clause, making Bernadette set him up with a crazy girl from her martial arts class. while they don't hit it off, she asks Leonard out to be her date at a wedding where she admits she'll probably put out. He agrees.