The phrase itself probably was meant to be a pithy little joke to ridicule liberals. The stark reality of where it comes from and what it is intended to accomplish makes it no longer amusing or even tolerable. Here is something I found that I think explains it well:
For the first time in our history, Americans have to be fearful of what they say, of what they write, and of what they think. They have to be afraid of using the wrong word, a word denounced as offensive or insensitive, or racist, sexist, or homophobic.
We have seen other countries, particularly in this century [this was written in the 20th], where this has been the case. And we have always regarded them with a mixture of pity, and to be truthful, some amusement, because it has struck us as so strange that people would allow a situation to develop where they would be afraid of what words they used. But we now have this situation in this country [America]. We have it primarily on college campuses, but it is spreading throughout the whole society. Were does it come from? What is it?
We call it “Political Correctness.” The name originated as something of a joke, literally in a comic strip, and we tend still to think of it as only half-serious. In fact, it’s deadly serious. It is the great disease of our century [the 20th], the disease that has left tens of millions of people dead in Europe, in Russia, in China, indeed around the world. It is the disease of ideology. PC is not funny. PC is deadly serious.
If we look at it analytically, if we look at it historically, we quickly find out exactly what it is. Political Correctness is cultural Marxism. It is Marxism translated from economic into cultural terms. It is an effort that goes back not to the 1960s and the hippies and the peace movement, but back to World War I. If we compare the basic tenets of Political Correctness with classical Marxism the parallels are very obvious.
First of all, both are totalitarian ideologies. The totalitarian nature of Political Correctness is revealed nowhere more clearly than on college campuses, many of which at this point are small ivy covered North Koreas, where the student or faculty member who dares to cross any of the lines set up by the gender feminist or the homosexual-rights activists, or the local black or Hispanic group, or any of the other sainted “victims” groups that PC revolves around, quickly find themselves in judicial trouble. Within the small legal system of the college, they face formal charges – some star-chamber proceeding – and punishment. That is a little look into the future that Political Correctness intends for the nation as a whole.
This was written in 2000. The writer’s predictions are now proven to have been prescient. This excerpt was taken from The Origins of Political Correctness by Bill Lind. The whole thing is worth a read.