I suggest you watch "The Room" first and then watch what the others suggest. Not only are you going to lower the bar so low, that it's going to hit the Mariana Trench's bottom and sink straight to hell, or, as they call it in "Preacher', further south, but you will see what a Polish writer/director/actor/producer can do. Now If you are looking for something fucked up, so disgusting that you will be ashamed of the human race and of yourself, watch "Serbian Film" that film is disgusting, strange and, most important of all, it's made by Europeans. Only Europeans are able to create high grade shit and legitimately call them films.
But I suggest watching Preacher. It's a good show.