The thing that I saw when I was little that traumatized me was "It", based on the book by Steven King about the clown. I walked through the living room when my dad was watching it right at the part where the clown pulled the little boy down into the rain gutter on the street, and he laughed and his teeth were all sharp...I had to start sleeping in a room right next to my parents instead of my bedroom, and I was scared of anything clown-related for quite a few years!
But I caught it on Lifetime recently, and it's such a dorky movie! And Seth Green was in it, when he was about 12, which I thought was funny.