Jimmy and Billy Joel loop their voices on an iPad app to form a 2-man doo-wop group -- singing "The Lion Sleeps Tonight" by The Tokens in 4-part harmony. Subscribe NOW to The Tonight Show Starring Jimmy Fallon: http://bit.ly/1nwT1aN Watch The Tonight Show Starring Jimmy Fallon Weeknights 11:35/10:35c Get more Jimmy Fallon: Follow Jimmy: http://Twitter.com/JimmyFallon Like Jimmy: https://