Malibu Beach Vampires.
Words do not exist to describe how bad this movie is. In fact, I'm not entirely convinced it is a movie in any meaningful sense, it seems to consist of a bunch of women in bikinis pretending to be vampires randomly intercut with song and dance numbers. Though I only survived twenty minutes before ejecting it from the DVD player so perhaps it makes some kind of sense eventually.
In my defence I should add that I only watched it because the only way to get a copy of a bad B-movie that some friends worked on years ago was to buy a box set of bad B-movies for $5 and I thought I might as well see what the others were like. I can now safely say there's a reason why the movies sell for $0.50 each.