It's acapella.
AND it's a parody - 'Rollin' Down the River' - for which I may cause certain people's panties to get bunched. Lloyd knows, I'm certainly not making fun of the original. May do a Copper's thing and adjust the tunage so it's not so blatant, or at least change it to major key so the I, IV and V chords would work and it can be capella. *shudder*