Wow this does seem very very very far out there. However I do have to admit that this is not a concept that I have ever though about.

This trailer is not really safe for work nor is it for those with a squeamish stomach. You have been warned.

Wikipedia:

The Human Centipede (First Sequence) is a 2009horror film starring Ashley C. Williams, Ashlynn Yennie, Akihiro Kitamura and Dieter Laser, directed by Tom Six.[1] It tells the story of a crazed doctor who surgically joins three victims together, mouth to anus, to create a “human centipede“. The film has won several awards at international horror film festivals, but has received mixed reviews from critics.[2]