Jim Carrey Does American Idol

American Idol will get two very special guests tonight: Jim Carrey and Katherine McPhee.

Jim Carrey is there to promote his new movie Horton Hears A Who, and rumor has it, he'll be dressed up as Horton himself. The contestants were lucky enough to attend the premiere this past weekend.

Jim is supposedly a huge AI fan, and even bigger fan of Simon. Something tells me Jim's appearance will outshine Katherine's performance.