Afrojack, left, is joined by surprise guest Pitbull during his set on the second night of KIIS FM's Jingle Ball at Nokia Theatre LA Live on Monday, Dec. 3, 2012, in Los Angeles. (Photo by Chris Pizzello/Invision/AP)

Photo by: Chris Pizzello

Afrojack, left, is joined by surprise guest Pitbull during his set on the second night of KIIS FM's Jingle Ball at Nokia Theatre LA Live on Monday, Dec. 3, 2012, in Los Angeles. (Photo by Chris Pizzello/Invision/AP)