I have a white dotty minkee nappy with a scarfed penguin on it, so it could be worn all Winter, rather than having a Santa or "Happy Xmas" embroidered on it, which would be very annoying in January, iykwim
But then I would use a nappy all year round regardless of what is on it! If you wanted a nappy specifically for xmas day you'd probably be better of with a wrap, as that could be worn all day instead of the hour you'd be lucky to get from a pocket nappy. I'm trying to get round to knitting a xmas pudding soaker, and pale blue longies with embroidered snowflakes on them, to feel a bit seasonal!