Havent been "scared" by a movie since I was kid, but the scene in Poltergeist where the clown drags the kid under his bed scared the ++++ out of me. I had a clown that looked exactly like that in my room at the time. That scene pretty much affected me for life, clowns still give me the creeps.
Same for me. I must have been about 6yrs old when I saw the preview of this on tv. They showed that clown dragging the kid under the bed and it terrified me.