In this episode we find out that Phoebe is pregnant, but the best part of it has to be the apartment switch. Monica and Rachel think that they know more about Chandler and Joey than the guys do about them. A personal quiz is put together by Ross and Chandler and Joey bet the chick and the duck that they'll win. Monica and Rachel bet their apartment and after a tense, long and hilarious game the guys win and Monica and Rachel move out.
This is definitely one of the best episodes of the season and of the entire show.