The final scene of [REC]. Some freaky fucking shit going on there. Just went upstairs in the dark and had the image of some naked possessed chick with a hammer stalking me.
*spoilers if you plan to watch it*
Brilliant film. Fair few moments when I shouted "DAMN!" and jumped a bit.
First contact with the xenomorphs in Aliens and Vasquez shouting "LETS ROCK!!!!" (also happens to be my message tone)
The 1st time you see the xenomorph in Alien and the nasty set of inner jaws