Purple People Eater (1988)

A kid (Neil Patrick Harris) plays the old novelty song Purple People Eater and the creature actually appears. The two then proceed to help an elderly couple (Ned Beatty and Shelley Winters) who are being evicted by their greedy landlord. Also with Peggy Lipton, Chubby Checker, Little Richard, Thora Birch and Dustin Diamond (aka: Screech in Saved By The Bell).