The Bru Code

I had a very colorful college life. Twelve years ago, I met a set of wonderful friends at the university. We call each other BRU (shortcut for BRUHA or bitch) Back then, cellphone belongs to the filthy rich students and the only means of communication that was much common was pager. But we don’t have pager too. I remember one schoolmate of mine has a pager and she would request me nightly to leave her a message. That was cool! But I and my friends’ means of communication is a paper and a pen.
So when we have to meet out of the university we would leave a note on the main gate of the campus. Or leave a note on the mirror or beside the Saniflo toilet of the university. But we don’t use our names, we used a code – the Bru Code. We were five and all of us have a code that’s only ours. And we use the code up to now. Can you guess what code am I?