Thursday night's "Daily Show" opened with quite a bizarre sight: Pint-sized teen pop star Justin Bieber sitting at Jon Stewart's desk, wearing a suit and introducing Admiral Mike Mullen. He even did Stewart's signature pen-toss.

But just as Bieber was about to get into the situation in Egypt, the real Jon Stewart emerged in a purple sweatshirt holding a skull, revealing the situation to be a "Freaky Friday" (or "Vice-Versa") type swicheroo. The skull can change them back, but while Bieber is desperate to get out of the "haunted house" that is Stewart's body, Stewart has a hard time saying goodbye to his new-found youth.

Watch the entire exchange in the clip below, and see what happens after the boys switch bodies and Stewart finds an unwanted "addition" to his lower back.