Without being too graphic, what is the most disturbing scene that you've ever witnessed in a film (not rated NC-17)?
I'd probably have to go with the chastiste scene about an hour into 'The Passion of the Christ.' It's the only film scene I've witnessed in which the violence in so brutal that I have to turn away from the screen.
I know this is lame, but I have a thing about not liking fire, so there was a particular scene in 'The Hills have Eyes' that had me watching through my fingers. On a more emotional level, I think at the time I found the last scene of 'Dancer in the Dark' really hard to watch as well.