Stevie Wonder walked into The Anaheim Marriott during NAMM 2017. An artist, Grayson Erhard just happened to be performing "Superstition" in the hotel lobby as Stevie passes. The audience alerted Grayson to Stevie's presence, to which Grayson told Stevie he didn't yet know the lyrics to the second or third verse. So Stevie joins him on stage and whispers the words.
Magical moment.

http://www.billboard.com/articles/co...l-lobby-busker