M. Night Shyalaman's The Happening.
The premise: something mysterious is causing thousands of people to drop what they are doing and commit suicide on the spot. It's a Hitchcockian premise for sure, but with an emphasis on the cock. This movie features some astonishingly absurd scenes, such as Mark Walberg trying to negotiate with a house plant, Zoey Deschanel's character outright admitting to being a wooden actress, a granny who headbutts windows, a hillbilly who shoots obnoxious children, and people being chased by a stiff breeze.
I think it is the best worst movie, because of the high production values, big names, and the genuinely sincere attempt to provide a thought provoking, terrifying, ecological parable. (It fails in every respect). It is that self-seriousness that makes it all the more hilarious to watch.