The Human Centipede (First Sequence) (2009)

I found the plot summary for the movie on IMDb:

Two pretty but ditsy American girls are on a road trip through Europe. In Germany, they end up alone at night with a broken car in the woods. They search for help and find an isolated villa. The next day, they awaken to find themselves trapped in a terrifying makeshift basement hospital along with a Japanese man. An older German man identifies himself as a retired surgeon specialized in separating Siamese twins. However, his three "patients" are not about to be separated but joined together in a horrific operation. He plans to be the first person to connect people via their gastric systems. By doing so, he plans to bring to life his sick lifetime fantasy, the human centipede. Written by Producer Ilona Six

In Germany, two American women and a Japanese man fall victim to a demented surgeon who plans to recreate a horrific operation with humans that he performed on his three beloved dogs: reverse-engineering Siamese triplets by attaching their digestive systems. Written by MuzikJunky

I must say this is one of the most fucked up and bizarre movie I ever met. It makes you think " who would even come up with this idea let alone acted in the movie. Though strange, a must see movie. Can't wait to see the second on.

Here's the trailer: