I love the episode where Phoebe teaches Joey how to speak french, and at the beginning when she's speaking it, Rachel gets turned on.

Phoebe: Oui, bien sur je parle Français! Qu'est-ce que tu penses alors?
Rachel: Oh... you're so sexy!
Joey: Well, so, will you help me? I really wanna be in this play.
Phoebe: Sure! Tout le plaisir est pour moi, mon ami.
Rachel: Seriously stop it, or I'm gonna jump on ya.