The Geordie duo together with Britain's Got More Talent host Stephen Mulhern appear on stage in costume for the final audition of the series.
The trio are said to have hidden in dog outfits and performed a DJ set.
"It was one of the moments of the day," a source told The Sun newspaper today. “Everyone was spent having watched loads of auditions but Ant and Dec thought it would be a good way to finish things off.
“The boys and Stephen had dog outfits made especially and performed a DJ set which went down a treat with the crowd despite no one having a clue who they were. The judges were in stitches when they stripped off at the end.”
It's claimed BGT judges Simon Cowell, Amanda Holden, Alesha Dixon and David Walliams had no clue about the trio's real identities until they revealed their faces at the end of the performance.
Auditions for Britain's Got Talent continues Saturday nights on ITV
Acts need three or more yeses to get through to the next round, where they stand the chance of making the live shows.
Last week's episode saw acts including the Gomonov Knife Show who shocked with their dangerous audition, which saw Simon Cowell end up in the path of flying knifes.
Finally, 13-year-old dancer Akshat Singh went one step further as he got the latest golden buzzer of the series. After auditioning, Ant and Dec ran out on stage to send the teenager straight through to the live semi-finals.
Britain's Got Talent airs at 8PM this Saturday night on ITV.
As always, straight after you can tune in to Britain’s Got More Talent on ITV2 with Stephen Mulhern.
The Britain's Got Talent live shows begin later on in the year.