Meghan Trainor stops by the Tonight Show Music Room to perform "All About That Bass." Jimmy Fallon - wood block, bass drum, Casio keyboard Meghan Trainor - vocals, triangle Questlove - hand clappers Mark Kelley - kazoo Kamal Gray - xylophone James Poyser - melodica Captain Kirk - ukulele Frank Knuckles - bongos Tuba Gooding Jr. - kazoo, apple shaker, banana shaker Black Thought -- tambourine 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://Facebook.com/JimmyFallon Get more The Tonight Show Starring Jimmy Fallon: Follow The Tonight Show: http://Twitter.com/FallonTonight Like The Tonight Show: https://Facebook.com/FallonTonight The Tonight Show Tumblr: http://fallontonight.tumblr.com/ Get more NBC: NBC YouTube: http://bit.ly/1dM1qBH Like NBC: http://Facebook.com/NBC Follow NBC: http://Twitter.com/NBC NBC Tumblr: http://nbctv.tumblr.com/ NBC Google+: https://plus.google.com/+NBC/posts The Tonight Show Starring Jimmy Fallon features hilarious highlights from the show including: comedy sketches, music parodies, celebrity interviews, ridiculous games, and, of course, Jimmy's Thank You Notes and hashtags! You'll also find behind the scenes videos and other great web exclusives. Jimmy Fallon, Meghan Trainor & The Roots Sing "All About That Bass" (w/ Classroom Instruments) http://www.youtube.com/fallontonight #FallonTonight #ClassroomInstruments #JimmyFallon