As long as there is Christmas, there will be attempts to spruce up and breathe new life into Mariah Carey's most enduring contribution to pop music, her 1994 holiday classic "All I Want for Christmas Is You." Mimi has sanctioned a a bass version, a house version, an Extra Festive version, a SuperFestive! version with Justin Bieber. But the rendition she performed on last night's Fallon, alongside Jimmy Fallon, the Roots, and a chorus of actual children, is by far the best spin put on this thing since the Phil Spector-inspired original. Few people could pull off the classroom-instrument arrangement with the grace of the "eternally 12" Mariah, and if there's any perfect time to act like a child, surely it is Christmas.