I had always thought I had seen C.H.U.D. mainly because without any hints I can immediately tell you that "C.H.U.D." stands for "Cannibalistic Humanoid Underground Dwellers." But turns out, I was wrong!
If I had seen it, I would have remembered that the cast is kind of amazing. John Heard is the lead, Daniel Stern is also one of the film's heroes, and John Goodman and Jay Thomas have small rolls as a couple of cops who sexually harass a diner waitress before getting ripped to shreds by some C.H.U.D.s.
The movie tries to toss in some commentary on homelessness, government corruption, and toxic waste, but doesn't quuuiiiiiitttte work as political satire. It does however nicely capture early 1980's NYC grittiness, a time in the city's history when it wouldn't have been that unbelievable to learn that there were cannibals living in the sewers.
C.H.U.D. is currently streaming on Amazon Prime.