CNN anchor Anderson Cooper snapped on live TV during a fiery discussion with prominent Donald Trump supporter and political commentator Jeffrey Lord.
"If he took a dump on his desk, you would defend it?" Mr Cooper said during the interview.
Mr Lord appeared shocked by the attack, before breaking out in laughter.
"I mean, I don't know what he would do that you would not defend," Mr Cooper said. "I mean, you're a loyal guy, I think that speaks well of you."
The verbal blow came after Mr Lord defended Mr Trump over allegations the President called former FBI director James Comey "a nut job" in his meeting with Russian officials, just a day after firing him.
Mr Cooper's comment has gone viral on Twitter, where it has been hailed as "the greatest moment in network news history".
Mr Cooper has since apologised to Mr Lord.
"I like having your voice on here and I think you're an important voice to have, so I'm sorry I was a little crude. And you defend the President very well, and that's your job," he said.
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