Do you have one movie that scarred you for life? I mean... not in the sense that you can't watch it anymore or anything like that. More along the lines of: you do things now (or DON'T do things now) because of that movie.
For me, that movie was Salem's Lot. The 1979 David Soul version, not the 2004 Rob Lowe version.
I watched this movie with my parents, and I think a couple of my aunts and uncles. I was 10.
Before seeing this movie, I used to love keeping windows open at night. A nice breeze would come through my bedroom window... I could get a glimpse of moonlight shining on my bedroom walls. It was all so serene. And then this show damaged me.
In this movie, you learn that vampires can only enter your home if they are invited. And they like to float up to your bedroom window and come in that way. If you keep your windows open (curtains or blinds wide open, too)... they will trick you into letting them in. If you're a smart person, you keep your windows shut and your curtains/blinds drawn, too. Then they can't see you, but most especially... YOU CAN'T SEE THEM!
Since that most memorable night, I have never slept with my windows open. Oh, I've had "bedmates" who have tried. They even tricked me by waiting until I was asleep to open the windows on their own. Of course, I eventually awoke to a lovely breeze floating over my body, and then shrieked like a banshee! Immediately following the banshee shrieking-- a body-hurling leap to the window to bang it shut and draw those curtains before Nosferatu could weasle his way in. Hell no. Hell TO THE NO!
So that's my "scarred for life" movie. And I'm not ashamed.