I read about this book called, "The Elf On the Shelf" on the Design Mom blog. It reminded me of a story Parley told me last year. There is a family we know that has one of Santa's elfs that lives in their house every year during December. When the kids wake-up each day the elf is in a different part of the house. He reports back to Santa each day how the kids are doing. When the kids start acting up, the mom says, "remember, the elf is watching." One day, their 4-year-old boy who sometimes gives his mom a run for her money, was being a little on the naughty side. His mom said, "remember, the elf is watching." To which the 4-year-old replied, "I don't care about no stinkin' elf anymore!"
I didn't realized that there is actually a book and an elf that you can buy. I might have to save my pennies for next year :)