Awesome variable for the term "X-mas" which in turn is a bastardation of the winter holiday celebrating the birth of Christ, "Christmas". Not necessarily referring to a Christmas with sex.
Merry Sexmas And A Happy New Year!
What Christmas turns into if you have sex before opening presents.
May also refer to the act of spending most of the 25th having sex.
"We celebrated Sexmas instead of giving gifts this year."
"I love Sexmas, it's the most wonderful time of the year."