Along with elevating white nationalists and giving airtime to conspiracy theories, Tucker Carlson has made something of a tradition of insulting Democrats' intelligence on his Fox News show.

Yesterday, he trained this particular weapon on Hawaii Senator Mazie Hirono, calling her "America's Dumbest Senator," and one person who emphatically wasn't having it was liberal commentator Keith Olbermann, and he hit back in the most epic way possible.

Referencing a hilarious—and extremely viral—gaffe Carlson made on air earlier this week, Olbermann put him firmly in place with a perfect tweet response.

Olbermann's tweet response was a reference to the moment on Monday night's edition of Fox News's Tucker Carlson Tonight in which Carlson seemed not to know the capital of Canada and mispronounced it in a very strange way when identifying it.

"So if the question is, 'What is the capital of Canada?' For the record, it's a place called Ottawa."

Carlson pronounced the city's name "uh-TAO-wa" instead of "OT-tow-wa" like everyone else in the world.

The moment went viral Monday evening.

As usual on his show, Carlson's reason for lambasting Senator Hirono was for something fairly innocuous.

Earlier this week, Hirono made news for pointing out that the term "sexual preference," which prospective Supreme Court Justice Amy Coney Barrett used on Tuesday during her confirmation hearings, is considered outdated and offensive by the LGBTQ community, because it suggests that sexual orientation is a choice.

Coney Barrett apologized for the error.

But Carlson, apparently, was not so gracious, sarcastically lambasting the Senator for the correction in his show yesterday.

"The economy is in shambles and there's a presidential election in three weeks, but luckily, America's dumbest Senator, Mazie Hirono of Hawaii, is upset about the right thing: the term 'sexual preference.'"

Later in his remarks, Carlson also called Hirono "truly the slowest person to hold public office in the history of this country," a pretty rich accusation for someone who doesn't know the capital of one of the countries that borders ours, as Olbermann so pithily pointed out.

And on Twitter, many people were right there with Olbermann's clapback.

Tucker Carlson has a long history of insulting Democratic women's intelligence. Earlier this year, he called Senator Tammy Duckworth "a deeply silly and unimpressive person" and a "moron," and accused the Purple Heart recipient of hating America.