Joey has a one night stand and wants Rachel to dump the girl (Erin) for him. Not only can’t Rachel do it, but she and Phoebe become friends with Erin and arrange for Joey to go out with her again. Joey decides he really likes Erin, but Erin decides there isn’t a future in the relationship. Ross discovers that his Doctoral Thesis is in NYU’s library. When he goes to visit it, he finds that it’s in a remote corner frequented by couples engaging in sexual activities. He begins to patrol that area of the library, but ends up being a culprit himself. Monica runs into Janice, who invites herself to Monica and Chandler’s wedding.