Mel B hurled a cup of water over Simon Cowell and walked off the set of America's Got Talent after he joked about her high-profile divorce.
The snide remark, which occurred during a live broadcast of the show on Tuesday night (local time), left model host Tyra Banks in shock and producers desperately trying to pick up the pieces.
Giving his analysis after a dramatic performance from magician Demian Aditya, Cowell said his disappointment at the act was comparable to what the former Spice Girl had experienced when she first tied the knot.
"I kind of imagine this would be like Mel B's wedding night: a lot of anticipation, not much promise or delivery," he said.
Mel B is now embroiled in a fierce court battle with ex-husband Stephen Belafonte, who she claims bashed her and forced her into participating in threesomes.
Cowell's joke drew a comical response from Mel B, who initially laughed - but that didn't last long, and she picked up the cup of water in front of her and threw it at Cowell.
She then stormed off angrily, leaving Tyra Banks to say, simply: "Mel B is out. This is live TV, y'all."
Mel B allegedly left the building before producers caught up with her and convinced her to re-enter during the next ad break.
Speaking to Entertainment Tonight, Mel B said Cowell should expect to get water thrown at him again if he says something else inappropriate.
"I told him he was an a***hole and that was it - and he goes, 'Oh, whatever'," she said. "But you have to understand that tonight was a two-hour show. There was a lot of emotion."