The music mogul - TV's Mr Nasty - was ambushed live on American Idol last night, just hours after it was revealed that the hit show with the famous red book is coming back to our screens.
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Sir Trevor McDonald jetted all the way to LA to present Cowell with the book, which chronicles his whole life.
It was rumoured the reality TV judge was to be the first victim but the celebrities' identities have to be kept top-secret so they don't get wind of the surprise.
Cowell took it in good spirits when Sir Trevor rocked up with the red book, while his fellow talent show judges Paula Abdul and Randy Jackson looked on in amusement.
The full This Is Your Life - with Cowell's friends and family gathered together - will be filmed on Sunday.
Incidentally, Jordin Sparks won the American Idol final.
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