The situation occurred after circus act A&J performed a death-defying routine on Britain’s Got Talent.
It came to the judges to speak on what they had just seen but Simon Cowell couldn’t seem to find the words.
Simon appeared to get into a fit of giggles which was pointed out by Amanda Holden.
The mogul struggled to collect himself to give his verdict on the act as he couldn’t hold in the laughter.
“He’s so naughty!” David exclaimed from the other end of the judges’ desk.
Simon was still chuckling as he said: “Stop it, David!”
It appeared as though he was then ready to give feedback to A&J as he began: “I kind of agree with everything…”
However, he soon trailed off and started laughing again as David got up out of his seat.
“Pull yourself together!” David exclaimed as he slapped Simon in jest.
As he returned to his seat, Simon said: “David, don’t be disrespectful.”
Many of those watching at home couldn’t believe what had just unfolded and took to Twitter to comment.
One exclaimed: “KFKWKCKOWJDJWKCIISS DAVID JUST B***H SLAPPED SIMON IM SCREAMING #BGT.”
“I CANNOT BELIEVE DAVID JUST B***H SLAPPING THE F**K OUT OF SIMOn i BUSTED A LUNG #BGT,” a second declared.
A third said: “Simon Cowell getting the giggles is so infectious #bgt #britainsgottalent.”
“Don’t think I ever seen Simon lost for words #BGT @BGT,” a fourth shared.
While a fifth added: “Simon and David are like immature naughty school children, I love it hahahaha #BGT.”
Earlier in the programme, David revealed Alesha Dixon had a near-miss before she came onto the stage.
Her dress had “come off” just seconds before the judges were called to walk on by Ant and Dec.
David announced: “We had a wardrobe malfunction, about a second before we came on Alesha said ‘my dress has come off’.”
Alesha then confirmed it was true to Ant and Dec as she continued: “Literally two seconds before you said ‘the Britain’s Got Talent judges!’”
Britain’s Got Talent continues tomorrow at 7.30pm on ITV.