Anyone who isn't a raging homophobe, racist, sexist etc on the internet will get accused of this at one point. It is used to deride people for using more polite terms and phrases as being brainwashed by SJWs into using "Newspeak".
conforming to a belief that language and practices which could offend political sensibilities (as in matters of sex or race) should be eliminated
The phrase began to circulate in American communist circles in the 1930s and ’40s, at first as a straightforward term meaning “the proper language to use, or the proper position, for a member of the U.S. Communist Party to take on a particular issue,” says L.D. Burnett, an adjunct professor of history at Collin College in Texas. “It was used primarily to demand political orthodoxy.” Until some people within the party began to snicker about it, she adds: “It was also used jokingly — kind of in an eye-rolling, tongue-in-cheek fashion — to refer to those doctrinaire sticks in the mud.”
The term political correctness (adjectivally: politically correct; commonly abbreviated to PC or P.C.) is used to describe language, policies, or measures that are intended to avoid offense or disadvantage to members of particular groups in society. Since the late 1980s, the term has come to refer to avoiding language or behavior that can be seen as excluding, marginalizing, or insulting groups of people considered disadvantaged or discriminated against, especially groups defined by sex or race. In public discourse and the media, it is generally used as a pejorative, implying that these policies are excessive.
The contemporary usage of the term emerged from conservative criticism of the New Left in the late 20th century. The phrase was widely used in the debate about Allan Bloom's 1987 book The Closing of the American Mind, and gained further currency in response to Roger Kimball's Tenured Radicals (1990), and conservative author Dinesh D'Souza's 1991 book Illiberal Education, in which he condemned what he saw as liberal efforts to advance self-victimization and multiculturalism through language, affirmative action, and changes to the content of school and university curricula. It was also the subject of articles in The New York Times and other media throughout the 1990s.
Commentators on the political left contend that conservatives use the concept of political correctness to downplay and divert attention from substantively discriminatory behavior against disadvantaged groups. They also argue that the political right enforces its own forms of political correctness to suppress criticism of its favored constituencies and ideologies. The term has played a major role in the United States culture war between liberals and conservatives.