This is a frequent argument I get into. I really like this article. 

"The other favourite hipster defense is, of course, to claim that people are being “too politically correct” or “too sensitive.” This is supposed to be a pithy insult which indicates that the person pointing out offensive behavior is too uptight, and not really part of the freewheeling hipster movement, but in fact, it’s just silencing. Saying that people deserve to be treated like human beings and that discourse should be respectful has nothing to do with being too sensitive, and everything to do with genuinely believing that people should be treated equally."