Ashton Kutcher jokes that he's not allowed to be "punked", but in fact it has happened twice - the first time was a test run by producers before the show aired (he was constantly asked to walk through an X-ray machine at MTV offices). The second time occurred when Britney Spears got Kutcher's staff to turn against him. But plan backfired. Ashton realized what was going on, and got Britney to turn on his Punk'd crew.