We know Santa sees us when we're sleeping, and knows if we've been bad or good, but how does he really know? Could it be because he has eyes and ears in our homes, listening and watching all season long?

Some elves have traded in their workshop posts in the North Pole to be Santa's ultimate helper -- to become "The Elf on the Shelf." Christa Pitts is the CEO of The Elf on the Shelf and we asked her to share with us the secret behind the magic.

Does your family have an elf that's been particularly funny or naughty? Send us a picture! We're featuring an "Elf of the Day" every day on the show throughout December, and your family elf could be on TV! Just upload a picture to our Facebook wall and watch for your elf at 4 p.m. ET!