Donald Trump Wednesday night assured America that "nobody has more respect for women than I do," as he denied multiple allegations of sexual assault as conspiracy or fiction.

Then he called Hillary Clinton, the first woman to win the presidential nomination of a major political party a "nasty woman."

The final debate was Trump's last and biggest chance to appeal to the women voters who broadly reject him in every poll. Throughout the 90 minutes, Trump limited the interruptions that played poorly in the first debate, but Clinton's dig at him while talking about the Social Security payroll tax apparently pushed him over the edge.

Clinton said her payroll taxes would go up, and so would Trump's, unless he found a way to avoid it. Trump has not released his tax returns but has admitted, following reporting by the "New York Times," that he didn't pay taxes for decades after reportedly taking a near-$1 billion loss in 1995.

The GOP nominee then leaned into his microphone and interrupted, "such a nasty woman."

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It was a moment that stunned even observers inured to Trump's often brutal rhetoric. Twitter immediately alighted upon his words, with Clinton supporters proclaiming themselves #nastywomen. A Clinton supporter unaffiliated with the campaign purchased the URL nastywomengetshitdone.com and had it redirect to the Clinton official site.

Related: Debate Was Short On Immigration, But #BadHombres Was Trending

"Nasty woman" was spontaneous Trump, a seeming gift to Clinton on the spot. So was Trump's tart "your husband disagrees with you," when Clinton praised the Affordable Care Act. But even if he hadn't stepped in, Clinton was ready to further drive a wedge between him and the white women who normally vote GOP.

"He said women should be punished, that there should be some form of punishment for women who obtain abortions," Clinton reminded the audience. (Trump later backed off the comment, made in an interview with MSNBC's Chris Matthews.) "And I could just not be more opposed to that kind of thinking."

Clinton brought up equal pay and women's rights before the Supreme Court. "In the 1990s, I went to Beijing and I said women's rights are human rights," Clinton said. "He insulted a former Miss Universe, Alicia Machado, called her an eating machine."

"Give me a break," Trump griped.

In fact, he did call the former Miss Universe an "eating machine" in an interview with radio host Howard Stern.

Clinton continued, "He held a number of big rallies where he said that he could not possibly have done those things to those women because they were not attractive enough for them to be assaulted," she said.

"I did not say that. I did not say that," Trump interjected.

In fact, he did say that. "Take a look at her," Trump urged his supporters of the People magazine writer who accused him of pushing her against the wall and groping her while she was on assignment to write about his wedding anniversary. "Look at her, look at her words, you tell me what you think. I don't think so." Of the woman who said Trump had groped her on a plane, Trump assured his supporters, "Believe me, she would not be my first choice."

Clinton then added, "He attacked the woman reporter writing the story, called her 'disgusting,' as he has called a number of women during this campaign.

"Donald thinks belittling women makes him bigger. He goes after their dignity, their self-worth, and I don't think there is a woman anywhere who doesn't know what that feels like," Clinton said.

In the end, as with the Access Hollywood recording released this month of Trump bragging about what he can do to women, it's Trump's own words that may undermine him the most.