Santa Claus

Calvin: Well. I've decided I do believe in Santa Claus, no matter how preposterous he sounds.
Hobbes: What convinced you?
Calvin: A simple risk analysis. I want presents. Lots of presents. Why risk not getting them over a matter of belief? Heck, I'll believe anything they want.
Hobbes: How cynically enterprising of you.
Calvin: It's the spirit of Christmas.

~Calvin and Hobbes strip by Bill Watterson