It was Christmas eve, and Santa was really busy making his list and checking it twice, when there came a knock at the door. His wife comes in. "Honey, where do you want me to put your boots and gloves?" Well, Santa is very busy and so he's slightly annoyed by this trivial question, so he snaps at her, "Put them by the front door, and stop bothering me. I'm trying to get some work done."
He starts back to work, but a few minutes later an elf barges in. "Santa, we got all the toys wrapped, what should we do with them?" Santa snaps, "Stick 'em in the sleigh! Can't you see I'm trying to get ready? I don't want any more interruptions!"
But sure enough, as soon as he starts back to work, there is another interruption. An angel, standing at the door, says, "Santa, I have your Christmas tree. Where would you like me to put it?"
And this is where we get the tradition of placing an angel on top of the Christmas tree.