Spike Rat
A small rodent that lies underneath the folds of flubber of an obese man. The rodent survives in hot moist areas of the body living off of sweat and missed food particals. If is very docile and can be easily trained. Can grow up to the size of a toy poodle.
Did you see the Spike Rat that was living between Billy's flubber? I think the Spike Rat was eating cookie crumbs.