Going into the judges dressing rooms and taking some of their prized possessions might not be the best way of getting them on your side.
Smashing those items with a hammer is even less likely to help your chances.
Yet that is exactly what Mawhinney did, leaving Mel B, SofÃa Vergara and Howie Mandel stunned before revealing that every item had somehow survived.
Mandel's phone appeared inside a locked box that had been sitting in front of the judges throughout the audition.
The phone then began receiving texts from Mawhinney revealing where the other judges missing valuables had ended up.
Vergara's framed picture of her dog was hidden inside her seat cushion, while Mel B's bracelet was concealed in one of the famous Got Talent red buzzers.
"I don't know how you do it. I believe in magic but I loved it," Mel B said when giving her verdict, which was a yes.
Vergara laughed and said the "magic was very impressive". She also voted yes, adding: "I don't know if this was necessary, but it was very exciting."
Mendel called Mawhinney "charming, you've got a good look", but it was a no from the comedian, calling the performance "too slow".
Simon Cowell agreed on the length of the performance and said "you can't do that on a live show".
"Our audience love magic, which is exactly the reason I'm going to say yes."
With three yeses, Mawhinney progressed to the next stage and remains in with a chance of winning the cash prize.