The X comes from the greek for Christ and the mass is, well, mass. The amount of people I know who get annoyed about it and then, once explained, bluster around and sulk.

The ignorant are often quick to being annoyed. I used to pronounce Xmas exmuss, but now I say chi-rho mess. And does anybody know if the H. in "Jesus H. Christ" (usually attributed to Sam Clemens) is really from the eta in the abbreviation IHC XPC?

Ceci n'est pas un seing.