It may have already been mentioned, but "Kids" (1995) was very, very disturbing to me. Uncontrolled children, violence, underage sex, HIV.
I saw it in the theater with a couple of friends when it came out. The film made me physically ill. I walked out to the lobby for a few minutes during one scene, but went back and managed to finish it, but damn..it put me in a funk that lasted a week.
You take a walk and you try to understand
Nothing can hurt you
Unless you want it to... R.E.M./Pylon "Crazy"
My Story: Cruel Summer