Have you ever seen a movie so bad that the crowd starts heckling the film ? It's rare, but it happens. Depending on the theater you go to and the time you attend, you might find yourself laughing along to the audience's own version of Riff Trax instead of the actual movie. There's a sweet spot for hecklers. The movie has to be so bad that most people aren't enjoying it; a few people have even walked out while shaking their heads and talking about getting refunded. (If someone starts yelling at…