The scariest movie I've ever seen (and I've seen many horror and splatter/gore movies) is definitely
House of Haunted Hill (1999)... it was so scary and crazy that I wanted to turn the TV off, but I didn't. In Germany this movie is allowed for people who are 16, but I think this is too low for such scary moments. :blink: This movie should only be for adults.
I don't know anymore about most scenes because I watched this movie more than half a year ago, but I know that I was really shocked!
But I'm not shocked if I watch splatter movies (like Guinea Pig, Visitor Q, Naked Blood, Grotesque, Saw and so on...). I don't know why, I've been watching splatter movies since I'm 15, but I wasn't ever shocked by splatter effects.