C.H.U.D. 2: BUD THE C.H.U.D. (1989)
When a trio of friends snooping at the school science lab discover a corpse and accidentally let it roll away, they need a replacement fast. They find one at the local hospital, but this is no ordinary corpse, this is "Bud the Chud," a cannibalistic humanoid underground dweller - out on a killing spree.
Brian Robbins, Gerrit Graham, Robert Vaughn, Jack Riley, Tricia Leigh Fisher