Elves vs Fairies

Patrick McGee, republished on Roger Ebert's blog, warns against losing a tooth on the wrong day.

Santa had a son who fell in love with the Tooth Fairy's daughter. Because Santa could not abide such a mixing of the species, he had the Fairy's daughter killed. The Tooth Fairy responded by killing Santa's son. So began the blood-feud. Elves and Fairies have fought and died by the thousands over the ages. But, most critical, is what happens on Xmas Eve. Should a child be unable to prevent the loss of a tooth on Xmas Eve, it's possible that the Tooth Fairy and Santa end up at that very house at the same time. When this happens, the resulting battle destroys several city blocks.

I should have known.