the line that you say to someone you do not know or barely know in response to them calling you bro. They may think they are cool or are chill and call you a bro. However, by saying don't bro me if you do not know me, you are telling them that he is in fact not a bro and does not have the right to call you a bro. One must understand what a bro is in order to say the line.
Stranger: What up bro?
You: Dude who are you? C'mon man seriously how dare you! Don't bro me if you don't know me.