Do you know why it's done? Is it to bribe Santa, or to say thank you for the gifts under the tree?
Well, perhaps to modern minds it is, but the tradition goes back further than Christmas trees. Way up here in Scandinavia we know that the one we need to please is not Santa, the one bringing the gifts, but the house elf. We know, or at leaste we used to know, that in every house and home there is an elf living. He's the one who blows out the candles we forgot to blow out before we went to bed, he's the one who puts the keys in the middle of the table when we just can't remember where we put them, the one who wakes us just in time to make it if we skip breakfast when we forgot to set the alarm. That is, when he's pleased with us.
He's also the one who hides the keys so well you just can't find them, turns off the alarm, spills the coffee all over the floor, ties your shoestrings together in ten thousand knots when you are in a hurry. When he's displeased with you.
On Christmas Eve he expects you to share your meal with him, both to say thank you for all the good things he's done for you during the year but also to show that you recognize him and admit that he actually is a part of the household.
So for your own sake I hope you left him something to eat?