I have a selfish neighbor that sits in her house every year. She never gives out candy, she just sits inside watching TV with her porch lights out.
Some kids invariably go up to her house and ring the doorbell, but she doesn't answer the door, she just sits inside. It drives me nuts, but there are usually some moments of karma when a young kid yells at her through the window.
I don't understand her situation. This is not a poor woman, I live in a nice neighborhood where everyone else participates. She is politically active in the town, talks to all of the neighbor kids, she just doesn't give out candy.
This year, in a moment just thinking mean thoughts, I came up with this one. I could install a big, heavy glass case on her lawn with a bunch of candy inside it. It would be the physical manifestation of what she does to the passing children.