Last year, five days before Christmas, my oldest son Luke came home from school saying he really wanted an "Elf on the Shelf" from Santa. This is a kid with zero interest in toys, who, a month earlier, had to be hogtied to sit down and come up with an actual Christmas list. And now, with Santa’s workshop winding down, and all of the presents made and wrapped, here he was offering up something that he truly wanted. Dagnabbit. An Elf on the What? “He’s one of Santa’s helpers who comes to live with you and tells Santa if you’re naughty or nice,” Luke informed me. “Nicholas in my class has one, …