At Halloween, don't let anyone in.

Do you know why in our town, inside every house, there is a sign that reads: 'At Halloween, don't let anyone in' ? No?
Once, a little girl lived here, in this very town, went to the same school you go to and played in the same park you play in. She especially loved to play at the pond. This little girl was pretty. Too pretty. The other girls in her class were all very jealous of her. Dangerously jealous.
One day in the autumn, the little girl went to play in the park, but she didn't come home at nightfall. People were looking for her everywhere, but eventually they gave up.
A few weeks later, at Halloween, one of those jealous schoolgirls disappeared from her house. The next Halloween - another. And then another. This last girl's
parents said she vanished just after opening the door to someone who seemed to be scratching it...
Eversince, every Halloween someone goes missing and is never seen again.
And that's why you should never let anyone in at Halloween.