This is useful stuff. Strange to find it on imgflip! Anyway, here's a bit more on the topic:
The history of the word “Xmas” is actually more respectable — and fascinating — than you might suspect. First of all, the abbreviation predates by centuries its use in gaudy advertisements. It was first used in the mid 1500s. X is the Greek letter “chi,” the initial letter in the word ???????. And here’s the kicker: ??????? means “Christ.” X has been an acceptable representation of the word “Christ” for hundreds of years. This device is known as a Christogram. The mas in Xmas is the Old English word for “mass.” (The thought-provoking etymology of “mass” can be found here.) In the same vein, the dignified terms Xpian and Xtian have been used in place of the word “Christian.”
