https://www.youtube.com/watch?v=BYO2oxDv_ZU
I just bought this DVD, and if you're into blues, or the Stones (or both like I am), you gotta pick this up. It was a "surpise concert." They claim it wasn't planned, but you can clearly tell it was. But the audience just thought they were paying to see Muddy Waters, and about 20 minutes in, Keith, Mick, Ian, and Ronnie all walk in and sit at a table, then join Muddy on stage. Then about 25 minutes in, Junior Wells and an afroed Buddy Guy join in on the jam session.