We start with the classic-but-mostly-forgotten Allan Sherman* version of "The Twelve Days of Christmas":
Which, of course, brings to mind "The Twelve Pains of Christmas" by the Bob Rivers Comedy Group. There're a slew of YouTube versions available, but I particularly like the World of Warcraft variant:
And then there's the Futurama episode, "A Tale of Two Santas":
And should you be a follower of the Flying Spaghetti Monster, well, here's how to make your own Xmasified/Winter Solstice version (see a big one here).
But as my late father would often say, it's just not Xmas without "Deck us all with Boston Charlie, Walla Walla, Washington and Kalamazoo..."
*Incidently, Sherman's complete works are available in a set called My Son, The Box. I really should do a post about my adolescent obsession with Allan Sherman songs someday, but for the time being let's just say it was all my friend Steve's fault. Well, him, and his two wonky brothers. And his four attractive sisters. And his flirty mom with her near-chef-like kitchen abilities.
Some of my non-seasonal Allan Sherman favorites:
"The Ballad of Harry Lewis"
"Eight Foot Two"
"Shake Hands With Your Uncle Max"