Let's see, now ...

How about "The Hole in the Elephant's Bottom"? Music Hall, but has found its way into Aussie folk clubs, largely due to Margret RoadKnight, who flatly refuses to sing it anymore. (It was almost becoming her theme song ... and the becoming was perhaps unbecoming!).

And then there is the "R Certificate Song" recorded by, but not written by, Bob Hudson, of "The Newcastle Song" fame many years ago in Australia.

Now, Kim C, you are presumably from the U.S. In Australia, "fanny" is certainly slang for a particular part of the anatomy, but it isn't the butt - and it is exclusively female. Put on a stage show of "Fanny by Gaslight" in Australia, and watch the boom in ticket sales!

Happy butt-hunting!
Shimbo