Dave Chappelle makes surprise appearance at John Mayer concert

John Mayer fans got an extra treat when a surprise guest showed up onstage.Mayer was performing at the Schottenstein Center in north Columbus Wednesday night.Towards the end of Mayer's set, he introduced comedian Dave Chappelle.Chappelle was greeted with cheers and applause.He further excited the crowd by welcoming Mayer to the Midwest, calling it the "home of the best."Mayer and Chappelle exchanged a few jokes before Chappelle sat behind Mayer's piano and began playing Beethoven's "Moonlight So