Trump's dis -- "such a nasty woman" -- came during one of his interruptions of his Democratic rival in Wednesday's final presidential debate.
Social media lit up as women came to Clinton's defense.
T-shirts emblazoned "Nasty Woman" went up for sale on e-commerce website Etsy.
"Nasty Woman" took off on Twitter, with actress Lena Dunham, who has campaigned for Clinton, spreading the word.
"RT if you're a nasty woman and it's made your life a freakin' pleasure," Dunham tweeted.
Trending were #ImANastyWoman, #ImANastyWomanBecause, #NastyWomenVote and #NastyWomanUnite.
Trump's comment immediately called to mind for many Janet Jackson's 1986 "Nasty" video, where the singer champions "nasty boys."
A new video mashing up Jackson's hit and Trump and Clinton debate clips quickly went viral.
Spotify streams of Jackson's song soared 250 percent after Trump's remark, CNN reported Thursday.
A CNN clip of Trump's "nasty" remark quickly garnered almost 27,000 views on YouTube.
News site Vox.com said that "calling Hillary Clinton a 'nasty woman' may have been the best thing Donald Trump has ever done for her campaign."
It noted the Clinton campaign purchased the web domain nastywomengetshitdone.com, which automatically links to the candidate's website, www.hillaryclinton.com.
Trump's comment came in response to a dig from Clinton to the effect that the Republican nominee -- who has bragged about his savviness in avoiding paying taxes -- might also try to get out of chipping in toward the nation's pension and health insurance programs.
In their third and final debate before the November 8 election, Trump accused Clinton and her campaign team of drumming up allegations that he has groped almost a dozen women.
"I believe," Trump said, "she got these people to step forward," accusing Clinton of running a "very sleazy campaign" and adding of the claims aired by several women dating back decades: "It was all fiction."
"Donald thinks belittling women makes him bigger," Clinton said.
"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."
