Trick Or Treat Fairy

We have lived in this house for 16 years. Every year we get a slip of paper in the mail box telling us when trick or treat night is going to be. We have no idea who does this. Not a clue. How bizarre is that? Some random secret neighbor sneaks around placing these in our mail boxes without being seen, without taking credit, without being a complete control freak and making it a bigger deal than it is. I do not know who it could be. I do not know anyone so complete unselfish as to manage this whole thing without wanting credit. And for so many years.
There is only one option, it must be the trick or treat fairy, not a real person. We have our slip, it appeared in the box, and the day is Thursday, between 6 and 8. This is going to be great!
Thank you Trick or Treat Fairy!