Katy Perry performed on American Idol Thursday night. Sadly, it was pre-recorded, leading to a chorus of boos from an audience that was beyond pumped for her to treat them to a live rendition of "Part of Me." While awaiting the week's American Idol results, the crowd was screaming and squealing in anticipation of Perry, one of the biggest stars in music today. For whatever reason, the stage manager and audience coordinator refused to let ...