Smitty

Smitty is one of the mutant dwellers of Futurama's underground New New York, a hard-boiled sewer detective who talks and carries himself like he wandered out of an old noir picture. He works the beat beneath the city's gleaming surface, gruff and world-weary, treating every case with the flat, cigarette-scarred seriousness of a man who has seen too much.

The joke is entirely in the contrast: a mutant living in literal filth delivering hard-boiled detective dialogue with total sincerity, and Billy West plays that sincerity completely straight. His gravelly, Bogart-adjacent cadence never winks at the audience, which is exactly why the pastiche lands as funny rather than just referential.