Hi,
Me and my girlfriend are in a relationship for the past 6 years, and since then she irritates me and all the time she say me bhaiya, it just so irritating that i don't know what to do? Please suggest your opinions. What should i do?

I thought we have some serious issue, you shouldn't bother about it , infact its not even a question to be asked. If she calls you Bhaiya to irritate you then simply do not react and don't even let her know that you have decided to ignore it, just don't react on it and be natural and she will stop using this word.