I knew a fellow named Les in the sixties (1960s) who played a seven-string guitar (he doubled up the treble e string--separate tuning heads). He sang the chorus

Mush a ringum a durum a dah, hah!
Wack fol the daddyo,
Wack fol the daddyo,
There's whiskey in the jar.

That was the first I'd ever heard of the song. Never knew what it meant. Great song, though.