Quote from Monica in The One Where Ross Finds Out
Monica: If you say stop, then we stop. Chandler: Stop. Monica: No, come on. We can't stop. We got three more pounds to go. I am the energy train and you are on board. [imitating train whistle] Whoo-whoo. Whoo-whoo. Whoo-whoo! [Chandler walks out of his own apartment] Whoo.