The best/worst movie in my collection is Ricki-oh! The Story of Ricky!
It's quite possibly the worst kung-fu movie ever made, it takes itself way to seriously, it's got so many plot and script holes the movie doesn't make any sense at all, not matter how many times you've seen it (and I've seen it hundreds of times). the video quality sucks, the movie is encoded in full screen 480i with black bars (yes the black bars are actually part of the video stream) giving it an effective resolution of 640x180.
The special effects are just flat out bad, most of the costumes look like they were made out of paper mache.
The movie is the best movie because it's just so overwhelmingly bad that you'll laugh your ass off. For the full effect you need to watch the English dub with English sub titles... the speech and text only match 5 times throughout the whole movie.
Also no one in the movie is capable of anything even remotely resembling kung fu... there are one or two guys with some reasonable muscle but they tried to make up for the lack of talent with the special effects, including big fake paper mache muscles, and fight scenes that are nothing more then some guy punching his fist through a paper mache stomach with chunks of rice cake and red water flying out the other side
For those of you who remember the daily show when Craig Kilborn was the host... the head smashing clip from the "5 questions" was from this movie http://imdb.com/title/tt0102293/