Fallon, Meghan Trainor Celebrate Curves With Classroom Instruments

'Tonight Show' house band and host back breakout singer's full-figured pop smash with xylophone and bongos

When Jimmy Fallon and the Roots invite a singer into their musical classroom, the results are always educational. For the latest installment of their "Classroom Instruments" performance series, the Tonight Show host and house band welcomed Meghan Trainor and her breakout hit, "All About That Bass," a soulful ode to full-figured female curves. 

As usual, the massive crew cramed into a small dressing room, utilizing an army of child instruments (tambourines, bite-sized bongos) and other diminutive noisemakers (ukelele, melodica). Their unlikely interpretation was just as good as the original, with their sparse percussion and intimate doo-wop harmonies anchoring Trainor's passionate lines about boasting "all the right junk in all the right places." (Side note: Props to keyboardist-turned-toy-xylophonist Kamal Gray for his sassy diva hand gestures.)

The booty-centric single was a sleeper hit for the 20-year-old singer. Last month, Trainor told Billboard she had trouble shopping around her infectious tune, with various label heads telling her, "We love it, but you have to reproduce it. You got to get it more synth-y, pop-y." But she eventually won over Epic Records executive L.A. Reid after performing the track on a ukelele.

Meanwhile, "All About That Bass" isn't Fallon and the Roots' first classroom rodeo: They previously teamed with Idina Menzel for an organic version of her smash Frozen ballad "Let It Go" and recruited Robin Thicke for a silly take on his ubiquitous "Blurred Lines." The recurring segment even dates back to Fallon's Late Night days, when octave-leaping vocal goddess Mariah Carey joined the crew for a quirky run through her holiday staple "All I Want for Christmas Is You."