Uh oh. Seems like there’s some tension on the American Idol audition set. The camera’s picked up this short war of words after Nicki Minaj began swearing at Mariah Carey and threatening, “I’m gonna knock you out” … sources tell TMZ. It all went down with Keith Urban sitting in between them and Randy Jackson sitting on the far end, next to Mariah. Producers ended the auditions for the day so the two judges could cool down. Producers of the show are very upset by the altercation and there now seems to be some worry about Mariah and Nicki co-existing for the long haul. I think a lot of people knew that acquiring Nicki Minaj to be an American Idol judge wasn’t going to be such a great decision. We’ll just have to wait and see what happens.