lol. What I mean bro, is that let's say you like to wear red shirts but everyone in your small town likes to wear green shirts (trying to pick the most PC example in today's PC world).
So you say, "man I hate all those green-shirts wearing bro's, I'm gonna move out to San Francisco/Portland/NYC/Seattle/Boston where red shirts are not only welcomed but celebrated!" So you move out to the big city to the soundtrack of Journey's "Don't Stop Believing..."
At first everything goes well, you see all of these symbols/paraphernalia/newspaper articles in your adopted city supporting the red shirts and you go to all of the red shirts social gathering or whatever, thinking "wow, everyone here is really into supporting the red-shirts clause." But then you slowly realize that not all red shirts are equal, there are skinny red shirts, fat red shirts, conservative and liberal redshirts, redshirts that sometimes like to mix it up and wear green-shirts and even "redshirts-wearing bros"!
It's human nature to discriminate and to stratify people into hierarchy. More people in one place leads to more structure, hierarchy and discrimination.