What's the worst horror movie you've ever seen?

"Manos: Hands of Fate", no doubt. I don't know if Manos is, technically, a horror film. But I see anything remotely to do with "worst movie ever" and I can't not plug Manos. There is not one good thing about it. Not even its 70 minute running time is a virtue. 70 minutes is a very long time to have to endure one's skull being pressed in a vice. I would rather watch Andy Warhol's "Sleep", a five hour experimental film of a man sleeping, than this godforsaken fetus one more time.