Stephen Colbert on Ben Carson's violent past on The Late Show

“Retired neurosurgeon and current tired person” Ben Carson is now leading Donald Trump in the polls, said Stephen Colbert on Wednesday’s Late Show. And in addition to questioning Carson’s religion, Trump recently called his opponent “super low-energy.”

But Colbert presented another side to Carson’s calm demeanor, airing a clip of Carson admitting that he wasn’t always so soft-spoken. When Carson was a teenager he would use “rocks, bricks, and hammers” against people. And when he was 14 he tried to stab someone.

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“I gotta say, that’s very impressive,” Colbert said. “He’s a neurosurgeon. He managed to harness his useful passion for stabbing people in the stomach into something more positive: stabbing people in the brain.”

Colbert then warned Trump to “watch himself” or the “good doctor will write him a prescription for 10 CCs of vitamin knife.”