Someone took the obvious joke, ran with it, and now The Human Centipede is a video game -- and it plays exactly like Centipede, only, you know, with humans. You are Dr. Heiter, avoiding cops and putting your human centipede out of its misery with your trusty rifle, and you can play it here.
I don't know if Tom Six had video game tie-ins in mind when he conceived the film, but it certainly scratches the surface of potential Human Centipede merchandise (including the Twinkie Centipede). I think we're not too far from a "beloved three-dog" from Weinerschnitzel (hold the fries) or custom branded butt-to-face underwear for the more sexual adventurous among us.
By the very nature of Heiter's experiment, let's rate this one M for Mature.