I like the "I know what you did last summer and sequel." Scream was good too, except I made the mistake of seeing Scream 2 before watching the first one. Needless to say, I spent half the movie asking what were they talking about when the first movie was referenced. My date wasn't too happy and since then, anytime we watch a sequel, he asks if I've seen the first one.

It took me a while to get the nerve to watch Carrie, The Shining (something about Jack Nicholson's characted still bothers me), and Friday the 13th without covering my eyes.
I still haven't gather the nerve to see The Exorcist.