A number of people who heard my talk yesterday about Xmas fell into my trap, saying they were offended that I replaced Christ with X.
A short lesson in a) Greek, and b) Christian symbology later and they all knew that X means Christ and if you try and replace Christ in Christmas by using the letter X (chi), then he's still there. I think they all enjoyed being let into the delicious irony that people who use Xmas as a 'safe alternative' don't know what they're doing.
And I got to draw a chi-rho and spell out ichthus in Greek for them. All good fun.