The Big Bang Theory Episode 2.07 The Panty Pinata Polarization

Penny is now a member of Leonard and Sheldon's group, so she must obey the house rules. After her third strike, Sheldon banishes her. Leonard gets frustrated with Sheldon about this because he and Penny are in a good friendly place with their relationship, but Sheldon is adamant. Leonard goes to Penny and asks her to apologize to Sheldon in order to make peace. She tells Leonard he's enabling Sheldon and she won't participate in that. Unfortunately this leads to a war between Sheldon and Penny with things escalating to the point where Sheldon steals Penny's laundry. Finally, Leonard goes to Penny and gives her Sheldon's kryptonite -- his mother's phone number. She uses it, Sheldon apologizes and all is well. Also, Wolowitz learns about the show America's Next Top Model and becomes obsessed with finding America's Next Top Model house.