Jimmy Fallon roped the Roots into playing a quirky version of "All I Want for Christmas Is You" with Mariah Carey last night on Late Night With Jimmy Fallon, performing the song on kid-sized toy instruments including xylophone, bongos, rattlers, wood blocks and more. A chorus of children chime in on background vocals and Carey takes it home with her untouchable voice. Then there's Questlove in his holiday sweater, looking like he'd rather be tearing it up on a full-sized drum set.