Donald Trump compared rival Ben Carson's "pathological temper" to a child molester's illness in his most jaw-dropping speech yet.
In his book, "Gifted Hands," Carson himself said he had a controlling "pathological temper" during his youth, which led him to try to stab a friend and almost punch his mother.
During a 95-minute rant in Iowa on Thursday, Trump let his opinion on the matter be known.
"That's a big problem because you don't cure that," the GOP presidential hopeful said at the rally. "That's like, you know, I could say, they say you don't cure - as an example, child molester. You don't cure these people. You don't cure the child molester."
He added: "We're gonna put somebody in the White House with a pathological disease."
In another bizarre moment, Trump performed a dramatic reenactment of the stabbing.
"He took a knife and he went after a friend - he lunged, he lunged and it hit the belt - and lo and behold the knife broke. Give me a break - Give a break," he said.
"How stupid are the people of Iowa? How stupid are the people of the country to believe this crap?" he continued.
Trump also claimed to have the inside track on ISIS.
"I know more about ISIS than the Generals do - believe me," he said. "I would just bomb those suckers. And that's right: I'd blow up the pipes, I'd blow up the refineries. I would blow up every single inch. There would be nothing left."
Viewers were left in utter disbelief, with the Washington Post writing: "Trump appeared to unravel on stage."
Carly Fiorina also came to Carson's defense after Trump's attack. She wrote on Facebook: "All the money in the world won't make you as smart as Ben Carson."
But Trump is unlikely to be bothered by her words.
He said at his speech: "I may leave here and you will say, 'what he said was not nice.' But I don't care - I'll go back to my life."