Season 3: Episode 59: The One Where Chandler Can't Remember Which Sister
There's a birthday party for Joey. Chandler, still getting over Janice, gets very drunk and makes out with one of Joey's sisters. However, after sobering up, Chandler can't remember which sister it was. Joey is excited because this sister has told him all about kissing Chandler, and how she thinks the two have a future. Chandler hides his memory loss from Joey, but the truth comes out when Chandler has dinner at the Tribianni's with Joey and all of his sisters and Chandler doesn't recognize the sister in question. Rachel complains about her new job to Monica when an unknown man, Mark, overhears the conversation. Mark tells her about a job opening at Bloomingdales. This makes Ross very jealous. Rachel's convinced Mark's just a nice guy, while Ross suspects that Mark has other motives. Rachel gets the job. Phoebe dates a Monica's noisy upstairs neighbor.