If you thought Jimmy Fallon would have Billy Joel on his show and not make him sing doo-wop on the air … well, you’d be right, but only on a technicality: The doo-wop had to wait for a commercial break, when Fallon and Joel joined with Joel’s band and special guest J.K. Simmons for a very giggly version of “The Longest Time.” It wasn’t quite J.K. Simmons’s tempo, but he swallowed his rage and sang the bass part anyway. Ooh-whooo-ooh!