Oh come on, "Hostel" was fun but really mild compared to the really screwed up foreign horror movies especially some low budget ones.
You should check out these movies that will mess you up:
"Men Behind The Sun". (Disgusting Hong Kong World War II horror drama about the Japanese torturing Chinese and Russians, they even used a real child's dead corpse for the autopsy sequence and killed a few real animals).
"In a Glass Cage (a.k.a. Tras El Cristal)": Utterly horrifying and dark Spanish horror thriller about an ex-nazi pedophile that has sexually assaulted, tortured and murders kids then after realizing the horrible things he did, he commits suicide but fails as it leaves him paralyzed to the neck. A young man becomes his nurse but unfortunately he happens to be a former rape victim from the sicko long time ago as he wants revenge. It has disturbing material such as a young boy stripped nude he is hunged by his wriests in chains hanging as the nazi takes a picture of him then beats him to death many times with a hard wooden plank, the disgusting sounds of the Nazi breathing in his special lung machine which he calls his "Glass Cage" or a young naked boy tied to a chair as he gets an injection of gasoline into his heart.
Inside (2007): Really disturbing and grotesque yet compelling French horror thriller that has to be seen to believed.
The Untold Story (a.k.a. Human Pork Chop, Bunman): Ugly and dark Hong Kong horror thriller based on a real story has some screwed up stuff like cannibalism, a woman being stabbed in the vagina with chopsticks, kids getting chopped up and more.
The New York Ripper: Fulci's most messed up movie yet! has women being tortured and sometimes butchered by a sick duck talking killer, there's even a broken bottled stabbed in a woman's private area.
Guiena Pig: What's there to say? sick crap going on.
Salo: Should i really explain this one? maybe you should see it.
Even some U.S. ones like:
Henry: Portrait of a Serial Killer is a very realistic and unique account on a actual murderer and has a disturbing snuff video sequence where he kills an entire family and even a Pawn Shop owner with a TV over his skull.
Bloodsucking Freaks: The most F'uped Troma movie ever made, 1975's notorious shock and torture feast puts "Hostel" to shame, it has chicks being naked as they are tortured even sexually especially their nipples sliced off, a chick getting her brain sliced and sucked out with a straw and dental torture.
Hills Have Eyes (2006): Greatest remake in recent memory! now this is ten times gorier then any hollywood horror flick with the exception of "Devil's Rejects" and "Grindhouse", just has the sheer disturbance of the original but more nastier.