I used to hang out with some kids that had a band back in college. I recall one night at the bar (they weren't playing, just having drinks) one of them sang his alternate lyrics for "John Deere Green" by Joe Diffie. I still remember (and sometimes sing them!)
In Porno Dreams
On a hot summer night
You know Billy Bob fucked Charlene
And her pussy was tight
The whole town knew Billy Bob had crabs
and they jumped onto Charlene
In porno dreams
They also did one for "Desperado" by the Eagles (not the fuckin' Eagles Man! I hate the fucking Eagles!!) lol. I don't remember it as well, but it was along these lines;
Baked Potato
Why don't you cook a little faster
You've been in that hot oven
For so long now...