Elf on The Shelf - A Christmas Tradition.
The real EonS is quite a scary looking character (IMO) but he arrives at your house with his Book.
You name him. Then tell your DC that for the duration of Dec 1st till Christmas Eve, he'll hide round the house and they have to find him.
He keeps a close eye on the DC and grasses them up reports to Father Christmas when he goes back to the North Pole.
He does nauty or nice things.
"Elf Pee" (green food colour) in the toilet.
Rice Crispies sprinkled on the floor
Sweet wrappers.
Nice things like a mug of hot chocolate left out for the DC or a letter.
You can do as much or as little as you like.
I made my own Elf (because I'm very mean and tight wad-ey) . First year a Dr Who doll. Next time an A Team doll.
Green and red felt to sew a tunic, trousers , hat, booties.
A little bag for a couple of sweets. I hid him round getting more tricky with the hiding places as December went by.
It's a lovely tradition, for young DC it's really sweet.
Mine are 11 and 13.6 . Elf seems to be a bit more like "Chuckie" 