I believe there is a direct correlation between how intelligent a person is, and how difficult it is to offend them. To put it bluntly: Stupid people are easily offended. I like this theory, mostly because it makes me look smart.
Often, people who are being offended are actually displaying cultural intolerances. For example: Bill grows up in the small town of Duck Nostril, Tennessee. Jill grows up in Squidlips, Utah. In Squidlips, the word "flurfle" means "to roll a ball". In Duck Nostril, "flurfle" is a vulgarity that means "to copulate". The two meet, and Jill uses the word in casual conversation. Bill is shocked and outraged. Jill realizes her mistake, and decides not to use the word in his presence again. But it's too late, Bill has already filed a suit for sexual harrassment.
A more realistic scenario: In Bill's hometown, the word "girl" is used interchangeably with "woman". There is no disrespect meant by the term. Children are "boys and girls", and adults are "guys and girls". Jill, however, feels that the word "girl" diminishes her, and is used by men to treat women like children. And in many cases she's right, but even so, Bill has the highest respect for Jill as well as all women. He simply thinks that "girls" are females of any age; that's simply what the word means to him. If Jill decides to correct him, that's fine. But if she is offended right away, then she is refusing to see other cultural variations of language.
I was at a restaurant one time with my stepmother. Our waitress kept calling me "Honey" and "Sweetie". After the waitress was gone, my stepmother asked me, "Doesn't that bother you? Don't you find it disrespectful?" I replied, "No, I'm not insane." I understand why some people would be offended by that sort of thing... I guess... but so what? This woman obviously meant the words as compliments, so why should I take them as anything else? The waitress must have grown up in an area where that was considered acceptable and complimentary. My stepmother obviously did not. And I was raised in some third place, possibly an alternate universe, where children are taught to consider the context more than the actual words.
But my stepmother is also very religious. That has little to do with the conversation above, but there does seem to be a connection there. Over-religious people are more easily offended than sane people. And having rejected science, over-religious people also seem to be a bit less intelligent. Okay, I'm overgeneralizing. Believe it or not, I have no problems with religion in and of itself. That's why I say "over-religious" - these are the people who not only worship a higher power, but also insist that everyone else do the same. These are the ones who go to church twice a week, listen to their pastor read Bible stories about loving your fellow man, then somehow turn that message into "why gay people should be killed."
But they're not the only ones. Everyone has thick skin these days, hence "Political Correctness". Thanks to PC, I have no idea how to describe someone. Like, "differently abled" - when something is bad, people don't like to talk directly about it, so they dance around the issue. So the more syllables a description has, the worse the condition sounds. That's one reason I don't like terms like "people of color" and "african american"... it makes it sound like there's something wrong with being black.
Question: in the "flurfle" scenario, did the genders sound reversed to you? You sexist pig :)
So, what offends me? Censorship. Sexism. Racism. People who put their own preferences above that of all others. People who burn books. People who think all TV shows/movies/books/video games should be wiped clean of anything they consider offensive, just in case a child should happen to watch one of them. People who think that this country should be ruled by religion. People who are offended by the nude human body (to clarify: it's okay if you don't particularly want to see nudity, or don't want kids to see it, or find certain bodies a "turn-off", but being "offended" by non-sexual nudity is unnatural and mentally unhealthy, IMO). But the bottom line is, what offends me most is people who are easily offended.
The difference between what is offensive, and what should be offensive, lies in the heart of the offender. Often the people who try to say something diplomatically, do so because the subject matter is offensive in itself. If you ever find yourself saying something like, "I'm not racist, but..." ...don't even bother finishing the sentence; you're about to say something racist. Heck, once in college, I overheard someone say, "I ain't racist or nuthin', but I just think all those n*****s should go back where they came from!"
Some other examples I hear a lot:
"I'm not racist, but I just don't think whites should marry blacks."
"I'm no homophobe, but I don't think they should show two men kissing on TV."
"I've got nothing against fags, as long as they stay away from me."
"I'm not sexist, but I think a woman's place is in the home."