I like this because it gets to the heart of a common misunderstanding. I can't tell you how many times I have heard people complain about Xmas - "Don't take Christ out of Christmas!" In reality, that is not what is happening. Actually, Christ is in the "X," the Greek letter Chi, which is the first letter used to spell "Christ" in Greek. It is an abbreviation, one used quite often by early Christians. So next time you see Xmas in a store don't tell them "hey, put Christ back in Christmas." Instead you might thank them for partaking in a ancient Christian tradition of referring to Christ with a Greek letter. I doubt many will know what you are talking about.