For the best fucked up movie as in THE MOST fucked up, for me it's Gummo.

I watched Funny Games in theaters in high school and it pissed me off so much. I literally shouted “fuck you” at a screen in a public theater. It wasn’t until much later that I realized that was the point.

I’ve been meaning to watch it again.

Spun (2002)

It's also entertaining and fun. Highly recommend

"Plague dogs" is the most depressing movie I have ever seen, I was in a funk for a few weeks after seeing it. In terms of conveying an emotion no other film has lived up to that movie for me.

I don't recommend it.

The Bad Batch was pretty fantastic, and those first few minutes especially are pretty fucked. With a cast containing Jason Momoa, Keanu Reeves, and a very sneaky Jim Carey, I'm honestly surprised it didn't get more attention than it did. Maybe it's the cannibalism.

Basically, the premise is that there's this big chunk of open desert around a town called Comfort out in the middle of a fenced off area in Texas where they dump criminals. It's got a very post-apocalyptic vibe. Highly recommended.

Blue Velvet? Probably up there...

I have never watched the full movie, but I think Eraserhead needs a mention.

Grave of the Fireflies

Can't go wrong with Riley Sterns. Faults and The Art of Self Defense are great wtf dark comedies.

Cannibal Holocaust. That’s the most fucked up thing you’ll ever watch

Snowtown has been the one in my life which has really stuck with me particularly because it’s a true story. The murder scenes were so prolonged and graphic.

Freddy Got Fingered and Sucker Punch come to mind..