DON'T MESS WITH ME!
"Don't mess with me, my money, or my man, and if you forget the last two, remember the first, DON'T MESS WITH ME."
I love this quote, however extreme it may come across to some, I think it's accurate. In its own right, this is the very essence of Girl code and Etiquette.
It is essential to be a sister at all times, and not in name only. Sometimes in an effort to BE Sisterly, we have to compromise on things that benefit us alone.
The essence of being a sister is putting the needs of your sister above your own, without compromising your dignity in the process. IF your sister likes a guy, and the guy likes you and not your sister, then you both need to move on. Never let a temporary situation-ship ruin your sisterly bond. IF you start a business with your sister, don't try to take advantage of her and abuse the relationship financially. IF your sister is out of line, let her know that she is out of line and don't allow her to look crazy. Be Sisterly, Duh!