What is a PC?

All my life I've encountered people who proudly proclaim that they are not PC--and inevitably those same people are racist, misogynistic, homophobic, anti-semetic, and all around misanthropic pricks. Usually they justify themselves with some sort of quip like "Hey man, I'm not PC, I'm just keeping it real," or "I'm not racist, I hate everybody!" as though that's better. They construct some caricature of this PC enforcer that's this oppressive, condescending nazi, then proudly proclaim that their inexcusable behavior is opposed to this non-existent threat to freedom.

I remember being raised on tales of these evil PCers, and maybe I'm looking in the wrong places, but I have yet to actually meet this creature. Maybe this PC caricature does indeed graze here and there, but I promise you that it's the opposite that currently overburdens the land. More often than not they have a show on Fox News. I've long begun to believe that this rare PC creature does not actually exist, but is just an imaginary ghost created to frighten children at night and justify our own hateful behavior.

I'm starting to think that PC is just a euphemism for not being a prick. I can understand why pricks everywhere would be opposed to that.