It's an unofficial rule in the pop world that every time Christmas rolls around, basically everyone must cover Mariah Carey's "All I Want for Christmas Is You." From Justin Bieber and Demi Lovato to Lady Antebellum and the cast of Glee, Mimi's holiday classic is virtually inescapable for the first 25 days of December. The same goes for K-pop, with the song being covered by every big star, every year, without fail. On Friday's episode of Music Bank, about 10+ K-poppers got together to close the show with a festive performance of the hit. We couldn't count everyone, but we spotted Ailee, miss A, TVXQ, f(x)'s Luna, Juniel, K. Will, SISTAR's Hyorin, KARA, 2AM's Jo Kwon, and 4minute's Jiyoon. The microphones were conveniently handed out to only the strongest vocalists, making this rendition pretty damn perfect. If KARA's Hara or Music Bank host, UEE, tried to take center stage, then this performance could've easily turned into The Nightmare Before Christmas.