There is only one answer to this question - and that is Plutonium Baby. It's from Troma Films, which I had no experience with before my art teacher, giggling all the way, showed it to us in class.
It is the worst movie ever made. It is SO bad that the film crew quit in protest. It features a scene near the beginning where, no kidding, the titular character (whose mom apparently suffered severe radiation during her pregnancy and now he has superpowers or something? idk) bites down on a very clearly PLASTIC fish, holds it between his teeth and pretends to eat it by shaking his head back and forth for nearly a full minute. It is the worst-acted scene I have ever seen.
There are no words for how bad this movie is. It makes The Room look like a masterpiece. At least The Room is so ridiculously bad that it's funny - Plutonium Baby is just a tragically boring trainwreck. And yes, I do now realise how terrible Troma Film's productions are, but this was my first experience with them, and I think I'm still in shock.
And I say this as someone who watched Dragonball Evolution AND Dragon Wars (already mentioned in this thread) while eating popcorn and giggling.
Hahaha - I actually enjoyed this one! XD It's bad, but it's just bad-action-movie bad - and I find that entertaining.