help! heard this in forever 21 december 2009!

please help! i heard this song in forever 21 in december 2009 but i dont know the artist or the name I know its is on the same mix that has kid cudi- day n night. its by a girl and the chorus has sort of an army marching song sound to it. it was before they switchhed to the christmas mix. please help im dying to know what song this was!

I heard a song in Forever 21 and I can't get it out of my head. All I really heard in the background (since I wasn't paying that much attention till I started taking a liking to it) was maybe kida or maybe a group of people just shouting "I am! I am, I am! I am! I am I am." It was by a female artist, she'll like sing the chorus then the "I am!" part come along I think. PLEASE HELP ME I'M LOSING MY DAMN HAIR XDD