The comedian was on hand Saturday for the Cincinnati Music Festival at Paycor Stadium -- where Snoop Dogg was one of the headliners ... and where Dave actually intro'd him before he came on stage and rocked the house.

Snoop's set was obviously awesome -- but even after he left the stage ... the show wasn't quite over (despite the place looking kinda empty toward the end). Dave had a few parting words for whoever was left ... including some raps of his own, which he spit live.

Check it out for yourself ... Dave delivered a little speech about the state of Ohio, and how happy he was that they were welcoming Snoop with open arms. It seems like he was also doing a little tribute to hip-hop at large, 'cause he launched into a Erik B./Rakim song.

Indeed ... DC rapped to 'Paid in Full,' this while the backing band played the beat on their instruments. It was pretty cool, and in the footage we have ... you can see the remaining crowd was vibing along.