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

<p><span><span>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!</span></span></p> <p><span>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.</span></p>