Here Prof. Steve Pinker lectures about the language of offensive words, how they work, and why people use them. Given that this forum is often littered with expletives and written abuse I thought that some understanding on the topic might be useful.
Warning: It is not possible to give a lecture about swearing, even a formal one, without using actual swear words. Some people may be offended. But if you want to know why you are offended then listen on.