Whoops, I thought you were advocating having Santa saying "kiss my ass" to players in game. It's impossible not to offend people on the subject of Christmas anyway. Say Happy Holidays, and people get upset. Say Merry Christmas, people get upset. Say nothing, and people think you're cold. In any case if it's Santa, Christmas is the more accurate holiday.

Assuming this gets put in, of course. It shouldn't be overly hard to program, though it's an Easter egg that wouldn't really get too much consideration until some of the final stages of the game's production.