The Jimmy Wilson Group is a band consisting of a whole lot of people named Jimmy Wilson for the duration of the gig. When they're not performing, they are, (among others):

Aaron Freeman (Gene Ween of Ween fame)
Mickey Melchiondo (Dean Ween)
Chris Harford
Claude Coleman Jr.
Bill Fowler
Mario, the Polish Rapper.

There's a mention of Old Jimmy Wilson in a song on Ween's album The Mollusk, in the song Waving My Dick in the Wind. He's an old man who dances if you give him a dime.

The group performs rather infrequently. They play Ween songs, Chris Harford songs, they're goofy.