Penny has become one of the guys around our guys. She dresses in sweats -- hair in a pony tail -- and she is not at all prepared when a new, very hot girl moves into the building. Leonard, Koothrapali and Wolowitz go crazy for this girl. They do everything for her, and it drives Penny crazy. She tries to compete with this girl, but she is just the new flavor - and they pay no attention to Penny. The episode culminates with the new girl getting a part on CSI -- and when she doesn't need the guys anymore, she dumps them. This episode ends with penny and the new girl getting in a knock down, drag out CHICK FIGHT!