The singer's reaction is so adorable when realizing crowd is singing the band's lyrics during their debut!

Not sure if it's the song itself or the singer's reaction to the crowd, but watching this video gave me some pretty sweet frisson!

Swiss/German girl duo BOY, performing "Little Numbers" at their first-ever Brooklyn show. In this emotional performance, Swiss singer Valeska Steiner, is surprised to hear the whole audience sing along, being that its their American debut.