In its purest form, “political correctness” means being nice, and learning what labels different people like to be known as; it means young people not refering to old people as geezers and straight people not refering to gay people as butt-pirates and other things like that.
It’s essentially having a sense of basic politeness towards groups of people. But others decry “political correctess,” usually after they’ve said some dumb offensive shit about people in wheelchairs or Middle-Eastern people or lesbians and subsequently been told to stuff it. Instead of just saying “my bad” and not making the controversial point again, they’ll lash out, ranting that the whole institution of “being criticized when saying things that are false” is bunk – political correctness has ruined Western Civilization because bigots can’t issue whatever nonsense they want without some “gay pussy fag” calling them on it.
Gay people talk about political correctness in a different way, though; to them, “politically incorrect” means unequivocally awesome things: Janet Jackson’s Nipple live for a Super Bowl audience of 90 Million Americans or a photo of a gay kiss on the cover of the Washington Post. It means wearing a pregnant nun costume for Halloween or admitting that your first sexual experience was at church camp and grinning about the irony while your uberconservative Christian college roommate gets peeved about it.
In those cases, gay people find it amusing to watch stodgy people froth with anger, while they themselves remain giggly and calm. This is equivalent to a moral victory, and it is why gay people decide that political incorrectness is fantastic.
The difference, perhaps, is that gay people can think of themselves as “politically incorrect” just telling the truth about their experiences; they could be esaying, for example, why they aren’t Christian anymore, why they feel no allegiance to a government that does not recognize them as full citizens, why they think the Religious Right is full of shit or what exactly their feelings are about having to road trip through Utah on the way to Vegas.
Incidentally, Stuff Gay People Like is politically incorrect. Of course expecting to define gay people through a simple list of traits expected is silly. And we will also come around to having our go at anti-gay people too, and won’t mince words. But we, like the gays, are awesome. And that is true whether it is politically correct to say so or not.