Believe it or not, Kitty, I heard it performed at the crew party/shanty sing which is held every year on the Pilgrim of Dana Point (i.e. a boat). So I kinda associate it with shanty singing, and anyway it went over well (as it probably does everywhere it is sung). Anything sufficiently funny can be sung at a shanty session, as far as I can tell.

I imagine A shellback chorus would be a bunch of old sailors backing up the shantyman--but I have no idea what THE Shellback Chorus is. :-)

Dustin