Jack Black stops by The Tonight Show to perform his legendary Sax-a-Boom with The Roots and read scenes written by little kids in Kid Theater before singing a Bowser revenge song. The Tonight Show Starring Jimmy Fallon. Stream now on Peacock: https://bit.ly/3gZJaNy Subscribe NOW to The Tonight Show Starring Jimmy Fallon: http://bit.ly/1nwT1aN Watch The Tonight Show Starring Jimmy Fallon Weeknights 11:35ET/10:35c Get more The Tonight Show Starring Jimmy Fallon: https://www.nbc.com/the-tonight-