dianavan, In the U.S. "P.C." stands for "political Correctness" which is a rather coercive kind of liberal orthodoxy. Be a free-thinker! Like all of us! It has a predictable, mechanical aspect, which is easy for conservatives to make fun of, because it's silly, and based on the current sense of what's okay on t.v. sit-coms more than anything else. Offline, once you get to know someone, you can make all sorts of funny rude remrks without giving offense. I love that, but I live in a cave with my kids, and don't get to do it as much as I'd like.
Take the Mel Gibson thing. We have a Jewish friend from Alabama who believes in the shroud of Turin. ( By co-incidence I've met the scientist who first studied the shroud and some Picassos I was interested in.) But she always seemed ambivalent about her faith so we didn't know what to say after she moved away. We settled on "happy Holidays, Christ Killer!" but that turned out wrong. She'd turned Episcopalian on us! We felt pretty awkward about it, then we didn't anymore.