Robotic Heckler

He turns up wherever someone in New New York is trying to do a comedy set, wheeling in to shout insults from the crowd before the performer has finished a sentence. A robot built, seemingly, for one purpose: to ruin other people's punchlines with his own.

The joke is entirely in the concept and the delivery — Maurice LaMarche gives him a nasal, needling contempt that never varies whether he's mocking Fry or a stand-up comedian, and the show wisely never explains him further. He's a running gag that earns its laugh by refusing to grow.