A cappella groups like McKinley High's "New Directions," from the hit show Glee and Florida State University's AcaBelles seem to be all the rage lately.
A fairly well-known group in this genre called Pentatonix has released the a cappella video to top all others and just in time for Christmas.
Their voices are so moving in this rendition of "Little Drummer Boy," one producer even shed a few tears. Remember, they aren't using any instruments. We don't know how they do it either.
Since it's posting on Nov. 25, the video has received over 15 million hits on YouTube.
Mobile users watch video here: http://bit.ly/1hGy9PP
The winners of NBC's third season of The Sing-Off made a name for themselves on the show with their rendition of "Eye of the Tiger." It secured them $200,000 and a recording contract with Sony.