The judge was asked (or maybe forced) to join David Walliams on stage to take part in Jimmy Tamley's ventriloquist act, but he was far from willing to play along.
While David gladly obliged, Simon stubbornly sat still on his stool before storming off the stage.
The contestant, Jimmy, was put in a difficult position because his act couldn't proceed without Simon, so Simon was eventually coaxed into returning to the stage after several seconds.
The routine finished with the two judges being herded into an over-sized packing crate, with the closing gag seeing Jimmy revealing it'd be mailed to "David's bedroom".
An obviously-annoyed Simon made his way back to the judging
panel, where he joked about murdering the production staff who'd allowed his
involvement in the segment.
"Why couldn't you have just used Ant
and Dec?" fellow judge Alesha Dixon asked when it came time for her to weigh
in.
Amanda Holden agreed Jimmy made a bad call, telling him: "It
was Simon's worst nightmare but it was great for the rest of us."
David Walliams was all smiles about having managed to torture
his boss for six minutes on live television.
When Ant and Dec
asked for his verdict on the performance, David joked: "This will be all
that Simon Cowell is remembered for."
Jimmy seemed shellshocked
by the carnage he'd unleashed on the Britain's Got Talent stage when Ant and
Dec checked in on him.
It was an eventful semi-final on Thursday that got off to an inauspicious start when Alesha Dixon's dress nearly fell off on her way to the stage.
