They've been the hosts of Britain's Got Talent for 13 series of the ITV talent show, but they've never sprung a surprise like this before.
Tonight none other than Ant McPartlin and Declan Donnelly took to the stage and auditioned for the show, and the judges and viewers watching at home and in the theatre audience had no idea it was them.
The cheeky pair disguised themselves in dog costumes alongside Britain's Got More Talent host Stephen Mulhern to perform as Disco Dogs as the last audition of this year.
They had the judging panel so convinced Amanda Holden and Alesha Dixon danced along to their act, thinking they were like any other act hoping to perform for the royal family at the Royal Variety Performance.
They also had Simon Cowell fooled right until the end when they removed the heads of their costumes.
"This is the sort of thing my son Eric would love," he told them.
"What a great end to the show this year. Thank you."
The good news is they got four yeses from the panel.
"We did it! After all these years," cheered Ant.
"That was the best thing I’ve ever bloody seen!! " said one stunned viewer.
"LOOOOOL now it makes sense," said another.
"Hahaha how did we not realise it was them!!!" asked another fan.
And another viewer said: "Hahahaha that was Ant & Dec and Stephen Mulhern all along! That really fooled me I was thinking a nice way to end the series I suppose but seriously?"
