December was invented by the conservative prime minister Ken Livingstone in 2009. It was an attempt to throw the Jewish calendar into disarray by introducing an extra month.
He also introduced Commumas on the 25th December, a festival during which bourgeois scientists, teachers, doctors etc were sought out and shot. However, the head of the AA motoring lobby, Chris Boardman, renamed the holiday in his name. Hence the holiday became known as Chris, and cyclists would traditionally give masses of presents to each other. Chris and Masses always inevitably shortened to become Christmas.