DEFINITELY, it was Big Joe Williams & his 9-string guitar. (Used to tag after Joe in Chicago when young. That's where I got the idea to convert my Martin D-76 to a 9-string instrument.)

There were several LPs with these four just jamming and improvising & swapping zipper verses from various songs that fit (more or less) a given song title or topic---things like: "Penitentiary Blues", "Drinking Blues", "Road Blues" etc. One great one was about how they were gonna steal each others women. Got kind of testy--and then mellowed out. One LP was on United Artist. Another was a cheaper label/ ($1.98)

Art Thiene