One of the things that makes Bonnaroo a little more special than your average music festival is the jam sessions. Some are organized, while others just seem to happen spontaneously. Earth, Wind & Fires set definitely fell into the latter category last night when they invited a couple of rappers up to freestyle toward the end of their set.

These weren't just any two artists, but Kendrick Lamar and Chance The Rapper, though according to the band it seemed to have just worked out that way. "I knew who he was, but it wasn't planned," band member Verdine White told USA today of Kendrick's appearance. "We stayed up there — what — 90 minutes? We were only supposed to be up there 70 minutes. You know, you just go. You don't think about it, you just keep going. He's in the band right now."

The two passed the mic, spitting some authentically off-the-dome raps, as well as playing hypeman roles (jamming as a vocalist can be kind of limited). Check out some footage from the set below.