Twenty million YouTube viewers can’t be wrong, can they? Ten Indiana University friends got together to sing in the mid-90s, and made a little video of their inventive (and hilarious) take on “The 12 Days of Christmas.” That video popped up on YouTube nearly a decade later -- and suddenly a cappella music was cool again. Fresh off the third of a five-album deal with Atlantic, SNC brings their signature wit, charm and golden vocals to the Overture Hall stage.