Lots of good ones in this thread, like.. LOTS of these are horrible horrible movies. That Kung Fu one... i couldnt even watch the youtube clip put up it was so bad.
This has to take the cake as the worst of all time though:
And to me the worst movie despite the praise was:
HATED IT.
The idea was actually pretty damn good, but my GOD it was boring, like seriously one of the most boring,slow,terrible movies i have ever seen. Me and my GF were SO BORED waiting for something... anything to happen. The only good part was the last 10 mins.