Quote from Rachel in The One with Phoebe's Husband
Chandler: I didn't know it was a big secret. Monica: Oh, it's not big. Not at all. You know, kind of along the same lines as, say I don't know, having a third nipple! Phoebe: You have a third nipple? Chandler: You bitch. Ross: Whip it out. Whip it out. Chandler: No, there's nothing to see. It's just a tiny bump. It's totally useless. Rachel: Oh, as opposed to your other multi-functional nipples?