Monica's excitement about her new place of work doesn't really phase Chandler, until she mentions that one of her co-workers (Jeffery) is the funniest guy she's ever met. Chandler tries to prove he's funnier. Phoebe and Mike take the next step in their relationship, by exchanging apartment keys. Then Phoebe's old flame, David (The Scientist Guy), comes to town from Minsk for a few days, putting Phoebe's emotions in conflict. Rachel and Ross hire a male nanny (Sandy) to care for Emma, but he's too sensitive for Ross's comfort. Joey learns life lessons from the nanny's puppet shows.