The one posted above from a year or so ago was done by John Valby, AKA Dr. Dirty. He's done many other bawdy tunes-think of him as an X-rated Weird Al.

One I heard on a jukebox some years ago:

FATTY CLAUS by Johnny MacRae

Here comes Fatty with his sack of shit
Here comes Fatty with his sack of shit
Here comes Fatty with his sack of shit
and all them stinkin' reindeer

I believe in Santa Claus
yeah, I believe that he's a prick
'cuz though he comes but once a year
it's enough to make me sick
him and his Christmas spirit
are really a lot of bunk
I'll have to bust my ass
for another year just
to pay for all this junk

CHORUS

Well, I believe in Santa
though he's got me in a mess
'cuz I'm over the limit on my MasterCard
and my Visa and American Express
While I'm sweatin' and grievin'
'bout this money mess I'm in
he'll be up there sittin'
ON HIS BIG FAT ASS
until Christmas comes again

CHORUS

Here comes Fatty with his Ho, Ho, Ho's
and there my money all go, go, goes
I'd like to punch him in his big red nose
make him wish he'd never came here