^^ What he said ^^
Being PC has a lot to do with having manners. You can say the same thing multiple ways, but usually there is a rude way of going about it and a much more diplomatic way of going about it. For example, there is a very large girl I know, but when I am describing her to people, she has a "dominating figure" accompanied with a gesture that makes the point clear. Yes, she's fat, but she's also a very good friend.
Homophobic slurs are unacceptable. Using "gay" in that manner is just wrong. There is nothing wrong with someone being gay, so why attatch negative connotations to the word "gay"? I don't get it and would rather err on the side of NOT hurting someone's feelings and pissing them off by using a word like "weird," "dumb," "strange," or "stupid" in its place.
As for the black man saying the N-word...that's his prerogative, and I doubt he will offend many black people using it, but I still disagree with that. Ugly words like that need to die. It is a terrible, hateful word.
Yes, some people really need to grow some thicker skin, and that is why I am against all those damned lawsuits over everything because that is just such an extreme and unnecessary overreaction. Those just escalate things. If someone gets offended with something, then just avoid the person and don't spend time with them and let them know they are engaging in boorish behavior. But don't fly off the handle and sue them. Although some people do need to grow thicker skin, others could be a little more sensitive (is it really that hard to not use certain words?) and avoid the issue altogether.