He read aloud negative Internet reviews of The Helmand, the Baltimore restaurant run by Karzai's brother, Qayum.
The contretemps started when Hamid Karzai, in a farewell speech delivered last week, thanked many nations for helping Afghanistan and its people, but pointedly left out the United States or any mention of the 2,000 American casualties incurred during years of fighting in the region. He also warned against trusting the USA. "America did not want peace for Afghanistan," he said, "because it had its own agendas and goals here."
That set Oliver off.
"Excuse me, Karzai," the indigant host of "Last Week Tonight with John Oliver" said. "I thought we were going to go our separate ways like adults ... but if you want to go out with backstabbing and low blows, that is no problem."
With that, he started reading off negative Yelp reviews of The Helmand -- and threatened to do even more if Karzai continued his ingratitude.
For his part, Qayum Karzai doesn't seem unduly concerned, or worried that business at his popular (and overwhelmingly well-reviewed) restaurant will fall off.
"It was funny," he said. "But they must have paid their researchers very well to find those negative comments."
But Qayum Karzai did address the connection the show tried to make between his brother and him.
"They didn’t do the due diligence to find out that my politics were not same as my brother’s," the restaurateur said.
Richard Gorelick contributed to this story.