Why I watch these movies, and Why I don't go spelunking

The long awaited film, "The Descent," finally arrived from Netflix today. The same night where the mother-in-law offers to take the kids for the evening to give me the the Wonderful Wife a night to ourselves.
After a dinner of wings at an establishment called Buffalo Wild Wing, a place which pales in comparison to my favorite wing joint, Wild Wing Cafe, we decided to head back home to watch an episode or two of "24: Day 5". When we got there we realized that my other Netflix pick showed up as well, the horror flick. I figured that I would have to watch it solo, in the dark quiet of the late night in my office above the garage after WW had gone to bed.
On my way to my comfy chair, I jokingly suggested that we could watch "The Descent" instead of boring old "24", and she said, "Sure."
Wha?
Huh?
Did she just...
"It's been over three years since I watched anything scary," she adds. Upon becoming pregnant with Kid A, she quickly grew a distaste for anything violent or tense on TV, and absolutely refused to watch any kind of thriller or horror movie. Over 36 months later, she has decided that tonight was the night to jump back into the ring.
"Are you sure?" I asked.
"Yeah, sure, it sounds good."
And it was.
This was one of those horror movies which makes you feel uncomfortable from the moment it starts. You don't know exactly why, but things just aren't right. Ok, someone dies right in the beginning of the movie, but from a car accident and not by any supernatural means. Ok, it was particularly shocking, and even a bit gruesome, but it wasn't the scary part of the movie. It served it's purpose for the story, and helped to set a disquieting mood for the rest of the film.
The protagonists of this particular story are a group of six girls who decide that instead of enjoying a weekend of basejumping, mountain climbing, white water rafting or any other of nature's thrills, the best way for them to spend their free time was exploring some underground caves. Boy, were they wrong.
They should have asked me what to do. I never would have sent them into that cave. Why? Because of the monsters, of course.
There was a good hour spent in this movie heightening the tension by following the girls through narrow, dark cave tunnels, each leading to another series of tunnels further underground, even darker than before. They are forced to push on after a (well named) cave-in blocks their known exit. It was just after one of the girls falls and breaks her leg that you see the first of the monsters. Not so creepy at first. Hard to see in the dark. But you know it's there. And the girls can't escape.
And I can't move from my chair.
And I am so uncomfortable.
And my poor wife is enduring this along with me because she loves me.
And she can't move either.
Normally I watch these movies alone and I can pause to take breaks whenever I feel too much pressure. I avert my eyes or press pause and breathe deep before continuing with the movie.
Not tonight. Not with my wife with me. Not if I am going to make it though this thing. We press on, taking only one bathroom break during the first hour.
And that's when all heck breaks loose. Thirty minutes follow of terror, on screen and off.
No, I didn't scream like a girl and embarrass myself. I may have jumped a few times and clutched at my heart for fear that it had stopped, but I didn't yelp or cry out once.
By the time it was over my entire upper body was numb from holding my muscles tense for the last 30 minutes. Yikes that was gross. Ugh, that was scary.
At the end of the movie, my WW jumps up from the sofa, grabs the "24: Day 5" DVD and replaces "The Descent" in the player.
"I don't understand why you watch these movies," she says. Same reason I don't go spelunking. It's all because of the monsters. And now I've seen the proof.