The star was forced to apologise to her boss' make-up artist, after she got carried away with some glasses of water, during filming for the new series.
Simon found himself rather wet after he made a series of jibes about his co-star, and while he wasn't too bothered about the soaking, it seems Amanda's actions riled other member of the crew.
Recalling the incident, Amanda said: "I gave him several warnings to stop it and in the end I threw the water on him and then had that moment where I think, ‘Oh god!’ and then I looked at his make-up artist and she was really cross.
"I looked at Simon and thought, ‘OK, I’ve got away with it’, so I carried on giving my criticism and he carried on going, so I picked up another glass of water and didn’t even look, I just chucked it over him and got him on the chest.
"He looked like Katie Price in a wet t-shirt competition but, you know, with pecs!"
She continued: "He was laughing his head off but his make-up artist, literally had steam coming out of her ears! She was so cross!
"I apologised to her. I got told off by everyone and he actually said, ‘No, I am happy to sit here’, he wanted to sit there and do the rest of the show because he looked hot in a wet shirt and he knew it, but they made him change his shirt."
Simon has regularly been winding Amanda up during the auditions, and teased that he had found her Achilles heel.
"There are certain things with her that really do annoy her," he explained.
"I thought it was quite funny, comparing an act to spending an evening with Amanda. But I found her Achilles heel because she really was annoyed about it.
"Then, as I was commenting on the act further, she thought it was just me talking about my night out with her, so she threw more water over me."
He added: "I’m used to it! I kind of wanted her to throw even more on me because I wanted to annoy her some more. It was making me laugh and I was trying to ignore the fact I was soaking wet. But I have found her Achilles heel now and it will be used more."
Consider yourself warned, Mandy.
'Britain's Got Talent' begins on Saturday (9 March) at 7pm on ITV.
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