Credit: Douglas Gorenstein/NBC

Jimmy Fallon famously hurt his left finger back in June, leaving him unable to play the piano. Chevy Chase hurt his right arm, uh, pleasuring himself to videos of The Mary Tyler Moore Show. At least that’s what the Vacation star told Fallon when he made a surprise appearance on Wednesday’s The Tonight Show. Then things got more awkward — Ariana Grande was mentioned — before the pair sat down in front of a piano to duet on “Heart and Soul.”