Sweet Jesus this has been bugging me. I remeber there was a cartoon show called “My Pet Monster” that was on in the late 80’s but there was also some movie that was similar that involved a kid who turned into a big blue monster or something like that. It was live-action.
YAAARG!
Did it have Fred Savage in it? If so it was probably Little Monsters.
I used to own the movie (god that was a long time ago) and it was also a cartoon. The kid got cursed by looking at some statue’s eyes at the beginning and he turned into the monster when he got hungry. I think it ended with him running super fast and catching up with a van and breaking the steering wheel or something. My brother used to have the stuffed My Pet Monster with rip-in-half-handcuffs
Here’s a humerous summary about the live-action version of My Pet Monster, complete with clips.