Extras whose one line steals the movie?

[soks]

Probably the best example is from "When Harry Met Sally": Meg Ryan demonstrates a fake orgasm in the middle of a crowded restaurant, leading the middle-aged woman at the next table to tell the waiter, "I'll have what she's having." Another favorite is the home health aide in "The Big Lebowski" who helpfully points out that the man in the gigantic iron lung has "health issues". Any others?