What's the funniest song you ever heard?

Why D'Ya Do IT, Marianne Faithful on "Broken English". Cracks me up every time I've played it....

Zappa's "Honey Honey Hey, Baby Don't Ya want a Man Like Me?' Sample lyric: "He trys to start the car, but the battery's dead; So he asked to use the phone, and she gives him some head...and thats the end of our story!"
Titties and Beer, another classic,as well!

I was in Denver 10 years ago and I heard a song on the local jazz station called:

"An Ugly Woman Told Me No"

...it was hilarious and I never found out who sang it, I only heard it once.

Randy Newman's "Short People" was a hilarious song also.

Oscar Brown Jr. has a tune calle "But I Was Cool" that will crack you up.

Zappa's "We gotta stick together", "Catholic girls",

I agree with Frank Zappa (adding "please don't eat the Yellow Snow"), Randy Newman (adding "Short People") and various Dr. Hook. I'd also add Warren Zevon (e.g. "Werewolves of London") and Tonio K (e.g. "Life in the Foodchain", "H-A-T-E-R-E-D").