You know, I think the problem most people have is coming into a movie with the wrong expectations. If you went to see Men in Black, or Jurrasic Park, or Final Fantasy, you shouldn't be expecting a new Citizen Kane, or even a new 2001. They're special effects movies. Same thing with action movies. Same thing with plot-based movies.
My nominations for crappiest movie ever would be quite limited in scope, seeing as I can't really remember more than a month back too clearly, particularly not with movies. I have little sisters, too, so I have all too many choices in the chich-flick department (and, believe me, any chick flick immediately qualifies as the worst movie Ever created. They are abominations, blasphemies against human dignity, terrifyingly, face-burstingly bad movies).
All in all, Meet Joe Black was probably the worst movie I've ever seen. By halfway through the first videotape, I was screaming, and I was preparing to commit seppuku to end the pain by the end of the second.
My second and third place would go to "The Bumblebee Flies Anyway" (funniest movie I have ever seen. I literally and truthfully fell on the floor convulsing with laughter towards the end, and this is absolutely not a comedy. It's that bad. Even the title is based on a false and ridiculously flawed premise. See this movie. You will wet your pants laughing at the "science" they have in it), and "John Q." (repulsive, propogandic tripe. It would be funny if it wasnt' trying to brainwash me)