WATCH: Olbermann uses Fox host Jeanine Pirro's own words to make case for Trump's impeachment

On Monday's episode of "The Resistance," host Keith Olbermann did something strange -- he read a monologue written entirely by a Fox News host.

"I did not write what follows, but it is perfect, so I will read it as it was written," Olbermann began, promising backstory later.

"We cannot have a country run by a president subject to ongoing criminal investigations, potential indictments and never-ending hearings," he began. "We cannot have a president under that level of scrutiny that inevitably leads to even more questions and more investigations. And irrespective of what happens to him, whether he's indicted or even guilty, it doesn't matter. His guilt is a moot point. He cannot take the Oval Office."

After finishing the monologue and pausing, Olbermann turned off his Fox News character and explained that what he'd just read was presented on Fox News on November 5, 2016 by host Jeanine Pirro, a well-known Trump supporter.

"It was her final argument for why you could not vote for Hillary Clinton, and must instead vote for Donald Trump," he continued -- and then offered the catch.

"I changed all the 'she's' to 'he's,'" he said with a grin. "Ain't I a stinker?"

Watch Olbermann use a Fox News host's words against her below.

NEW VIDEO: An unanswerable argument why Trump can't remain POTUS while being investigated. And I didn't write it! pic.twitter.com/WUfvbMLTy5

— Keith Olbermann (@KeithOlbermann) August 7, 2017