A common misconception: the Twelve Days of Christmas are the days leading up to Christmas day. As John McLaughlin would say, WRONG! The celebration actually starts on Christmas Day. And that's one to grow on.
Though I maintain that John Denver and the Muppets recorded the definitive version of the song, this take by Bob & Doug McKenzie, off of their album 1981 Great White North, is a close second. Now, I will start celebrating with a beer...in a tree.