The film tells the story of a German doctor who kidnaps three tourists and joins them surgically, mouth to anus, forming a "human centipede". Having completed the operation, the doctor begins training the centipede, while attempting to hide his actions from the attention of the outside world.
Tosh.0 had a very good summary of the movie last night. He very accurately describes the movie, but I don't think half the crowd realizes this. He does miss a few funny points from the movie though.
And this is just the first sequence! There is going to be a sequel!!!!111!!11!