http://www.nytimes.com/2015/11/09/nyregion/yale-culturally-insensitive-halloween-costumes-free-speech.html
the rules of polite behaviour aren't the same as the law.
generally we want legal protection for offensive behaviour because that is sometimes where truths appear. the kinds of people that society seeks to protect from offensive speech are those unable to defend themselves by answering eg minors, not undergraduates.
nevertheless, you are not necessarily making a valuable point by gratuitously offending people. maybe you are just being rude.
if you are going to seek to be be offensive, don't assume it means you are advancing culture. sometimes, it just means you are an arsehole.
on the other hand, don't moan about people expressing an offensive opinion. you can usually decide to ignore whatever it is you find offensive. there are people with much more substantial problems. making yourself a victim gives the offender a power you shouldn't offer them anyway.
it would be useful if people could distinguish these things.