Schwanz is also a euphemism for penis.

However, I doubt this is really the same song. First, the scansion of Wolfgang's sample verse doesn't fit the tune I posted. (I typed it in directly, and didn't try to MIDIze it myself, so there may be some simple syntax error.) Secondly, there is no attempt in the two verses I know to substitute a tamer - and non-rhyming - word for a cruder one. Nevertheless, my thanks, and I'll check your lead further.

I should also clarify, I'm not especially interested in dirty verses, just additional ones. I don't get much enjoyment out of gratuitous crudity. ;-}