The original poster for Tom Six's original The Human Centipede was pretty nasty, but only if you looked at it already knowing the premise of the film. It showed all three sections of the human centipede pressed up against a frosted glass pane, and it was a brilliant poster. Discreet enough to get away with being displayed outside cinemas and on the DVD cover, but explicit enough to give you fair warning about what you were going to see.
As a point of reference, and to give you the option of turning back now, here's that poster.
And now, here's what a 12-part human centipede looks like.
Actually, my first thought was that this is not just a 12-part human centipede, since every section has a few "hangers-on." These presumably aren't in the movie but have been added in here so that the poster looks, from a distance, on a foggy day, like it might actually just be a picture of a bug.
Really, this is brilliant marketing and great artwork, even if you do find the premise of the whole series too gross to ever be loved.
Since the poster for Lars von Trier's Antichrist showed Willem Defoe and Charlotte Gainsbourg fucking in a big pile of hands there's really no reason why this should be disallowed. After all, the only indecent exposure it shows is a bit of bum cleavage.
The Human Centipede Part 2 will begin a limited theatrical release in the US from October 7th, and will get a UK release … well, never, if the BBFC get their way.