"I kind of imagine this would be like Mel B's wedding night," Cowell began when it was his turn to give feedback. "A lot of anticipation, not much promise or delivery."
Before he could get to his punchline, the 42-year-old singer -- who is in the middle of a contentious divorce with her ex, Stephen Belafonte -- stood up and aggressively threw her cup in Cowell's face, soaking his shirt and hair, before storming off stage.
This isn't even the first time this season Mel's thrown her drink at her fellow judge. During the audition rounds, Cowell joked that she'd managed to get famous without knowing how to dance and ended up getting soaked.