The Holy Mountain. No smurfing contest.
Rantz and I tried to watch Beyond the Black Rainbow and it was intensely uncomfortable for reasons we couldn't pinpoint and we ended up turning it off before we even knew what was going on. That's probably next on the list.
Also The Devil's Rejects. Uncomfortable, godawful, stupid pointless crap, and I think I remember there being n abhorrent rape scene, but it's possible I am confusing it with another film. I hate Rob Zombie.