Xmas

In the future, the use of the word "Christmas" to refer to the holiday on December 25th has been completely lost in the mists of time, and replaced with the word "Xmas", pronounced Ecks-Mass. As such, the day has lost all religious connotations it had in the past. As pine trees are extinct, palm trees are traditonally decorated with festive lights. Being nude on Xmas seems to be quite popular. However, it is not wise to be outdoors after sundown on Xmas eve, because you'll probably be killed by Robot Santa, just like in the last Xmas in the 30th century

The origins of Xmas are told in The Story of Xmas; a play about Ebenezer Omicronian who is visited by six ghosts who foretell the coming of Zombie Jesus and reveals the reason the holiday changed its name. Mom is somehow involved.