We don't do it anymore since I moved away, but my little brother and I used to team up and scare all the kids that came up to our door. Here's how it would go:
I would be dressed as a scarecrow and sit on the front porch (dressed so it looked like I was a real scarecrow). I would sit perfectly still and watch the kids come up to the door right next to me. They would ring the doorbell and my little brother would come out. "Trick or treat!" My brother would say, "Well? Which one do you want, a trick or a treat?" If they said treat, I would reveal the hidden candy bowl and let them take a piece (usually scared the hell out of them). If they said trick, then Matt would just tsk and say, "Should have taken the treat" and close the door. Then I'd jump up and scream like a freakin banshee. I love Halloween.