Bob Rivers did a great one…
Another classic: “The Rest Room Door said Gentlemen”
http://website.lineone.net/~mredman/christmas/carols/comedy/comedy11.htm
Who put the stump in my rump-de-bump-de-bump?
Who took and jammed it in my rama-lama-ding-dong?
Who stuck the shoot where I poop-she-poop-she-poop?
Who was that man who rammed it in my can
And left me stranded on this Christmas tree?
It’s not quite accurate, but you get the general sense. Sung, of course, from the perspective of the angel on top of the tree. 
Da Yoopers Rusty Chevrolet:
http://www.stlyrics.com/songs/y/yoopersda5389/rustychevrolet224122.html
Chipmunks roasting on an open fire
Jackals ripping at your throat;
You’ll tell Carol, “You’re a skunk and a liar,
And you smell like a billy goat!”
Everybody knows some turkey under mistletoe
Helps to make the party blight.
Tiny sots with their red eyes aglow
Will find the pavement hard tonight.
They know that Santa’s been delayed;
He’s overloaded, overworked, and underpaid.
And every mother-F is gonna try
To shoot a reindeer with his piece as they fly by.
And so I’m offering this special phrase:
“Buy now! Just $19.92!!!”
You know you’ve been had, many times, many ways;
Merry merchants screw you.
Yes, I wrote it. No, I don’t get coal in my stocking every Christmas – I don’t hang a stocking.
sing to the tune of "The Little Drummer Boy…"
Said the night wind to the little lamb,
“Do you see the Scotsman?
Hiding in the bushes little lamb,
Watch out for the Scotsman!
A kilt he wears, a zipper you can hear
He will come up on you from the rear,
Sneaking quietly from the rear.”
I wrote that two days ago listening to the 24 hour Christmas music station in the car with cadolphin. I’m Scottish. I don’t schtupp sheep.
ABC, DEFG
HIJ, KMNOP
QRSTUVWXYZ
No ‘L’, No ‘L’…
OK, maybe it’s lame, but I thought it was pretty funny when I was a kid…
By some guys I hung out with in college:
Cthulu the tentacled Old One
Had a very evil brain
And if you ever saw him
You would go completely insane
All of the puny mortals
Used to laugh and call him names
They never let poor Cthulu
Join in any mortal games
Then one hellish deadly day
Cthulu came to say
Mortals with your souls so bright
I will dine on you tonight
Then all the mortals feared him
As they shouted out with pain
Cthulu the tentacled Old One
yeeeearararghhghgh!
It ain’t great art, but it’s very catchy.
Two.
There’s one I remember from when I was in high school but I only saw it as a printed page my brother’s friend had given him and I’ve long since misplaced it. It was a parody of “The Night Before Christmas” and it was all bathroom humor. I only vaguely half-remember snatches of it. Santa farting, falling off the roof(when out on the lawn we heard such a yell, we knew all at once the fat fucker’d fell"
One of these day’s I’ll go googling for it.
Enjoy,
Steven
Well, it’s an original song, not a parody, but I can’t help putting in a vote for “I Yust Go Nuts At Christmas,” and this link will take you to the lyrics and an audio performance of the song:
Check the balls on Howard’s collie
Fa la la la la… la la la la
I don’t know what happened to my comment but I said:
Hey, Zap, that was priceless.
Winklehoff! Winklehoff is king!
Or to quote the immortal Cheech & Chong:
Santa Claus wears a red suit; he’s a Communist.
And a beard and long hair, must be a pacifist.
What’s in that pipe that he’s smoking?
What about Allan Sherman’s Twelve Days of Christmas? (,“Aand a Japanese Transistor Radio”)
and isn’t it Jerry Mendlebaum?
The Restaurant Song
Chestnuts roasting in the microwave
Hash browns burning on the grill
Off-color jokes being told by the chef
And waitresses looking for a thrill
When you have to work
With turkeys and with imbeciles
It helps to make you lose your mind
Coffee-swilling busboys
With their eyes all aglaze
Will find it hard to sleep tonight
They know the owner’s on his way
He’s gonna yell and scream and stomp his foot all day
And all the kitchen crew is gonna sigh
They’re going to go and drink like fish until they die
And so I’m offering this simple phrase
To all us groveling restaurant crew
Although it’s been said many times, many ways
This job sucks, and the boss does too.
I remember something like that too, only a little different… Let’s see:
*'Twas the night before Christmas and all through the shack
The whole damn family was drunk off its ass
Grandma and Grandpa were singing a song
The kid was in bed flogging his dong
Ma, just home from the cathouse and I out of jail
Had just settled down for a good piece of tail
When out in the yard there arose such a clatter
I jumped off of ma to see what was the matter
Away to the window I flew like a flash
Threw open the window and fell on my ass
And what to my bloodshot eyes appeared
A rusty old sleigh and a bunch of reindeer
And a little old driver holding on to his dick
I knew in a moment the bastard was Saint Nick
Slower than snails his charges they came
He bitched and he moaned as he called them by name
"Now Dasher, now Dancer, up over the walls!
“Quick now, dammit or I’ll cut off your balls!”*
The rest I forget but it ends with:
I heard him exclaim as he drove out of sight:
“PISS ON YOU ALL, IT’S A HELL OF NIGHT!”