Gay Robot

A robot built by the U.S. military as a secret weapon, Gay Robot appears in a single Futurama episode as a prototype whose flamboyant personality undermines his intended function as a stealth assassin. He is enthusiastic, affectionate, and utterly unable to complete a mission without complimenting someone's outfit or breaking into show tunes first.

The joke is a one-note premise stretched exactly as far as it should go and no further: a lethal machine whose programming keeps colliding with his personality. Billy West plays him with total sincerity rather than mockery, which is what keeps the bit affectionate instead of cheap, and lets a throwaway gag become oddly endearing.