Nightmare Fuel: The idea that Curtis Danko died by being trapped in a kiln and it being turned on with him in it. It's even worse when it turns out that Michael and his friends locked him in there in the first place and the janitor accidentally turned it on while he was mopping.
Squick: When Uncle Fred is dressed as Cheesy the Clown, he drops his fake hand out down the front of his pants and offers $100 if a kid finds the hand. Remember, he's an old man and a zombie.
The Woobie: Curtis Danko is a tragic case of this. He was outcasted in his school, because of his Gothic appearance and taste in art.