One day a long time ago Santa was having a very bad week.
The elves were on strike for more pay. No, the elves were on strike for pay.
Due to a snow storm the raw materials to make the toys had not been delivered.
Mrs. Claus had forgotten to pay the utilities so the gas, water, and electric had all been turned off at the toy shop. The customer service agents at the utilities had all said that they would gladly turn them back on after the first of the year.
The toy shop was effectively shut down with only two weeks left until Christmas and Santa was still two million toys short of what he needed.
Santa was beside himself and had taken to drinking straight shots of tequila.
After his forth shot, there was a knock at the door. He stomped over to the door, jerked it open and yelled "Who the hell is it?".
A little angel answered "It is me Santa, and I have brought you this beautiful tree so that you too can enjoy the spirit of Christmas. Where would you like me to stick it?"
And from that day forward it has been a tradition to put an angel at the top of every Christmas tree