In the movie The Kingdom, there is a 30 minute or so action/chase sequence at the end of the movie when the Americans are attacked heading to the Saudi airport.
It was so intensive I couldn’t multi-task and do anything else, I had to sit there riveted and stare unblinking at the screen.
Little known, almost forgotten, one of the most horrifying things ever put on screen. I don’t think it was Paul Newman who was trapped under the log, but OMG. 
127 Hours, James Franco getting his arm caught in between those rocks. I watched some of it and I started getting a panic attack, and I had to stop watching.
The scene in I’ve Heard the Mermaids Singing, where the paintings get burned, even though it turns out not to have happened, but just to have been imagined. Still bugs me every time I see it.
Also, the scene where they kill the pig in Carrie, and pretty much any scene where a bad thing happens to an animal. The most disturbing scene for me in Single White Female is the puppy scene (I can’t even bear to spell it all out). There are whole movies I won’t watch, like the Will Smith version of I Am Legend, because I heard that something bad happens to an animal.
I don’t have to tell you which scene I FF through in Fatal Attraction.
Jon Favreau in Swingers calling the girl he met in the club. Repeatedly.
The trapped character was Joe Ben Stamper, Hank’s (Paul Newman) cousin.
For some reason, scenes involving horrible tortures leave me unmoved (albeit grossed out), but scenes involving people being socially embarrassed I find difficult to watch.
The whole movie is supposed to be stressful, the the scene in Cujo where the kid has a seizure really sticks out in my mind.
There is a website called doesthedogdie.com (I think, my browser won’t let me confirm since it’t under ‘games’) that will tell you in advance if an animal dies in the movie 
In Lincoln when DDL goes off on SF about their son’s death and about how he had to be the functioning one and how torn apart he was but had to hide it and be the strong one. That was my wife’s and mine exact situation after our daughter died. Yes I cry every time I see that
When they had to start swallowing the water in The Abyss to survive. I haven’t seen that movie in forever and it still makes me shudder to think of it.
Most recently, the crash scene in Flight - there’s a bit where one of the doomed flight attendants is hanging by her ankle from the door of an overhead compartment that just…
Any of the Russian roulette scenes in “The Deer Hunter.” Much, much earlier than most of the scenes described so far.
I would have went with the scene where Giovonni Ribisi’s character, the medic, gets shot. Just listening to him when he finds out that the bullet hit his liver, and there’s no chance of him living.
And then Upham standing there, helpless, saying “tell us how to fix you.”
The scene in AI when she leaves him in the woods. Say what you like about Haley Joel Osment, but that kid could freaking act, unlike most child actors. The sheer panic and terror and his certainty that if he could just be good, just have one more chance, she would love him…and her knowledge that love wasn’t enough… shudder I have a whole subscription’s worth of those issues. (It was interesting watching that movie with my family - all of us broke down sobbing at some point, in the theater, which none of us usually do, and all at different parts.)
Also, the baby in the bathtub in Joy Luck Club. Haven’t seen that move in 20 years, and that scene haunts me every time I give a baby a bath.
Oh god, I was screaming at my TV. All alone in the room at the time, talking to my TV. :smack:
I was so that guy (as opposed to, say, being money and not even knowing it)
I just laughed and laughed at laughed at that bit. Horrible nazi woman got bitten by her own snake…
Ok, perhaps not. But never viewed it with the sadness others seem to have.
I have a similar feeling with The Boy With The Striped Pyjamas.
Feeling sad for the family of the boy seems wrong to me. It might be careless to raise your child near a concentration camp, but if you’re the one marching people in their thousands to their death every day, whether you’ve educated your offspring about what your doing, or where to avoid seems irrelevant: You are the one who should not be having children (for the worlds sake).
The Human Centipede.
If you’ve seen it, you know the scene…
As soon as an animal - pet or otherwise - is introduced because I just know something bad is going to happen to it.
Also pretty much any scene in which a gangster is harassing someone for something totally innocent. Which is pretty much any scene in Boardwalk Empire with Al Capone in it.
The scene in Star Trek II where Khan is pulling the sand-slug babies out of their mother, slowly, while explaining how they enter the brain through the ear canal, then dropping them into the space helmets then . . .
. . . then I would usually find that an appropriate time to have to go to the bathroom or refill on popcorn.