This should be fun!

What's the worst movie ever made in all human history? The film so cringingly awful that your skin crawls and your blood runs cold? The film so bad you'd consider poking your eyes out vs being forced to watch?
My pick: Natural Born Killers. The stinker by which all others are judged. When I make a list of the "Bottom Ten" worst, I really have to make it 11 as I've set NBK as "winner" of the "Lifetime Acheivement For Suck Award." Nothing I've seen is so irredeemably awful as that one, so it's only fair I consider it as it's own catagory, a category of one.
What are some other choices for the Worst of the Worst?