Woo Hoo! Let's open up ourselves a case of Hateorade
TM
Batman and Robin: I know know obvious choice but this film will always remain the definitive how not to guide to making a super hero movie.
Highlander 2: The Quickining: Destroyed everything that was good about the first film in one fell swoop when the idea of making the mystic race of immortals that were the center of the series into "aliens".
Battlefield Earth: Fool! John Travolta was chewing scenery back when you were learning just to spell your name.
Lost in Space: When the campy 60's sci fi show was more logically written and better acted then the 1998 film it was based on, then you know there is going to be deep hurting to come. (Fun fact both Lost in Space and Batman and Robin share the same screen writer, who went on to win an academy award for writing the screenplay to "A Beautiful Mind" I guess the saying is true at first you don't succeed try try try again.)