The story
From crinkle (“to rustle”) + critter (“a creature; an animal”), because such creatures would likely make a crinkling sound as they moved. Compare crinklebutt and crinkler.
Etymology from Wiktionary, CC BY-SA 4.0.
crinklecritter
crin·kle·critt·erToday it means: Synonym of diapercritter (“an anthropomorphic creature or full-body suit made entirely out of a single (fully absorbent) diaper”). Full definition →