I do not know about you guys, but personally this word drives me insane, especially when complete strangers try to call it me. I start coming out with questions like who is your mother?, who is your father?, what makes you think you are related to me? are you another brainless moron that joined the armed forces?
That is a word for a family blood bond and should not be used how it is being used. You see psychology is in play here, you let your guard down around friends and family. When a complete stranger calls you "bro" usually some chavy brat, possibly from the Manchester area of England, you either let your guard down thinking this tool thinks he is related, or your back goes up and you become antagonistic.
For me I become antagonistic as I see through the psychology, but too many don't, they think they are just trying to be cool, when the reality is, we used to call these fools wiggas because of the way they spoke or behaved.
Please guys I implore you, stop using this pathetic term, it does not make you look cool, it does not make you sound cool, it simply makes you look like an ill educated twat putting it bluntly. Family is sacred so anybody ignoring this has no respect for the family unit.
This is just my two pennies, feel free to add to them in the comments. :D