The One with the Halloween Party (S08E06)

At Monica's Halloween bash, Phoebe takes to her semi-evil twin Ursula's nice-guy fiancé (Sean Penn), who may be engaged under false pretenses. Also, goofy costumes fuel a grudge match between Ross and Chandler; and Rachel's maternal skills are put to the test by a batch of tricky trick-or-treaters. (National Broadcasting Company (NBC))