There are certain rules that come with being a girl. Some we learned early… "Play hard to get"; "Never wear white after Labor Day"; "Always leave a man wanting more"; "A good bra is your best investment"; "Flirt without saying a word."

As we get older, though, the rules of being a girl manifest into the rules of sisterhood; a certain level of respect that we have for the fellow females in our lives – particularly the ones we call our friends.

Urban Dictionary defines the term girl code as "a set of useless, bullshit rules that girls use to govern and bully around their friends."

Ok, well we’re not talking about only wearing pink on Tuesdays, a la Mean Girls. We mean not sleeping with a friend’s ex or slipping your number to the guy your friend has been chatting up all night – blatant rules that are the basis of any friendship worth having.

Why, then, do so many girls abandon them?

We never thought we’d say this, but there’s a certain appealing loyalty to "bros before hos." Some girls are quick to abandon their friends – both single and taken – when a guy is involved at any level. Their need for whatever it is they are lacking from within shines like the North Star, and allegiance flies out the window faster than you can say "Merrill Lynch broker."

Let’s not forget, ladies, who’s got your back after Prince Charming wimps out. Never leave your female friends out to dry.

Stupid obvious.

Christina: Intuition told me that my friend Candace had a thing for the guy I was dating. I just sensed it. It didn’t really bother me, though, because I knew it had no bearing. I was the one he was interested in. It was me he took on dates and me who hung out at his place in the City and me he spent Valentine’s Day with. Quite simply, it was me he felt the attraction for.

"That’s just not what a friend does," was her response. "She violated the Girl Code."

And so we pondered… what exactly is the Girl Code? Because it’s not the bullshit Urban Dictionary is making it out to be. If Vince Vaughn and Owen Wilson had rules in Wedding Crashers we, as women, should have them also.  Play like a champion, yes. But don’t step on your friends’ toes to win.

When you interview for a job, they want to know experience level, educational background, and skill set. On a first date, you ask whether the guy has siblings, what he does for a living, where he's from. Well, when we meet female friends in Hoboken, the determining question should be, does she believe in and embrace the Girl Code?  

We define it as such:

The #1 no-no Never date or get the number of a current boyfriend, someone we are seeing, someone we are sleeping with, someone with whom there is already mutual interest, and especially not a significant ex. Men are not territory – but if we’re there or we’ve been there, you should not venture onto that playing field without a permission slip. The moral of the story is simple: how would you feel if the situation were reversed?

Users need not apply Your friends are not just there when you’re single and want people to party with. Nor are they just there when you’re going through a breakup and need support. They are your friends through every turn in life. This is a privilege. Do not abuse it.

We all know the story: Mister Right (part VIII) comes riding in on his stallion and you pull a disappearing act that would make Houdini proud. All of a sudden you are "too busy" to hang out or even call/text/email your friends back. Life begins and ends with Francois – who, by the way, you met only a month ago at Café Elysian and you still don't know the proper pronunciation of his last name.  Yet all of a sudden, life before Francois is a distant memory and a night out with friends is "childish behavior." Clearly, the only way dinner and drinks is happening is if the new boyfriend is included.

Then… WHAM! Francois dumps you.

Don't expect your friends to be there. You weren’t.

Never leave a girl behind Even if it means sucking up a lousy night every once in awhile, do not cut and run on your friends.

At the same time, be mindful of your friend’s reciprocal lousy night and do not ignore them for a guy. It’s a balance between pursuing a member of the opposite sex and still knowing how to be a friend. It is possible to maintain this equilibrium.

The "No your butt doesn't look fat" clause We’ve all seen it… the girl who jumped out of a J.Crew catalog chatting with the friend who is literally spilling out of her outfit from all sides. You wonder: (a) doesn't the latter own a mirror? and (b) why didn't her friend say something?

You may not want to insult your friend’s style, but Girl Code states you never let your friend walk out of her place in something that truly makes her look hideous. Find a tactful way of giving her the heads up (i.e. remind her how cute that little black dress in her closet is) It’s not nice to allow your friend to look bad so that you have the edge. Remember, karma is a bitch. You don’t have to be one too.

Be a gracious wedding guest If you are single or, worse yet, just out of a serious relationship when your good friend is about to get married… we know it’s hard, but suck it up and put on a happy face. Your friend probably realizes how difficult it is for you and it will not go unnoticed that you rose above.

Your day will come.

A note for brides-to-be We love you, we are genuinely thrilled that after all those 3:00 AM cry-fests you have found your soul mate, and we are excited to share in all the related festivities with you. This does not mean we need to hear about your wedding every time we talk. Just because you are getting married, the whole world does not revolve around you for the entire year leading up to the big day. Girl Code dictates that you must still be able to hold discussions not related to your dress, the centerpieces, the guest list, or your engagement ring. And, every once in awhile, ask what’s new with us.

Don’t go psycho bunny You meet up with one of your best female friends for a nice dinner at Lola’s and, after explaining your dating pool is particularly shallow right now, she smiles and tells you about this "great guy" she knows. Weeks later, she introduces you to her friend. The two of you hit it off right away and date for almost a year before he ends it with you for no discernable reason. Girl Code (not to mention Self-Respect Code) dictates that you are not allowed to become psycho or obsessive. It didn’t work out and you are allowed to be hurt, but he’s still one of your best friends’ friends. You must respect this.

Jen: True Story. I introduced my high school friend, Rachel, to my buddy Rob from college. Both were chronically single and looking for the "perfect match." The two ended up dating for nine months, broke up briefly, then got back together for another four months before Rob called it quits for good. Imagine my surprise when he called me a week later to tell me that one night Rachel (now his ex) let herself into his carriage house and stood over him as he slept. He woke up to find her at the foot of his bed. This was clearly NOT OK on many levels – but for our purposes, Rachel indeed broke the Girl Code. Though her extreme actions were all on her, I somehow felt that it indirectly reflected on me and that is not a good place to be in.

Note to the ladies, avoid making any pit stop between Zoloft-ville and Crazy-town when you’re on the dating train of a friend.  

Don’t pilfer When out with the ladies, if Girl #1 points out a guy that she is interested in, Girl #2 should avoid making a bee-line over to him to get his number for herself. Show some respect.

Two girls can be attracted to the same guy. It happens. Employ good judgment, though, and avoid simply elbowing your friend out of the way.

Respect Girls’ Night Out When said evening is described as a "Girls’ Night Out" that means it is for GIRLS ONLY. Consider it payback for all those tree houses and snow forts we couldn’t enter as children.

Don’t just leave the boyfriends and husbands at home – stop text messaging them every five minutes. It’s just poor form. Trust us, you can survive the night with only one check-in call and a few martinis.

Stop being the "Me too!" girl If your friend is telling a story, stop stealing her thunder – and her story – by constantly trying to one-up her. For example:

Girl 2: Oh that’s horrible. The same thing happened to me today, only I stepped in gum on the subway platform too. And when I went to scrape it off, I tripped and ripped my stockings and it reminded me of the time I was at my ex-boyfriend’s place for Christmas……

There is a fine line between providing input based on your own history and experiences, and interjecting unnecessarily. Let your friend vent, then relate where it is needed and when the moment is right.

Hop on the "woe is me train" for one stop Your friend is having a pity party. Guess what? You’re invited! What do you do? If you can, show up… lend an ear… let her pity herself for a few minutes, then take her to Frozen Monkey. Ice cream and sprinkles usually solves everything anyway.

Incidentally, said friend should do the same for you in your pity party time of need. To state the obvious, friendships are not one-sided.

Practice responsible friendship Yes-ing our friends to death is not really supporting them. It’s giving them false hope. True friends know they can tell the truth – even if it’s a harsh reality – and then leave the person to make their own decision. True friends also support said decision, even if we don’t like it.

Saying, "Yes, I think it’s a good idea for you to get back together with Ryan after he cheated on you, made you cry every day, didn’t want to hang out with your friends, and then blamed you for missing the game because you ‘walk too slow’" is NOT support. That’s irresponsible friendship. Girl Code is to protect each other. So say your piece, then let her make up her own mind. And don’t get mad if she doesn’t follow your advice. It’s her life.

Don’t be a hater We all do it, ladies. We are a bunch of haters. We see the human version of Barbie walk into a bar and we immediately find something wrong with her: she's too tall, her teeth are too big, she lost a war with the bedazzler, etc.  But you know what? You have no idea what is going on in her world. Maybe she's lost a family member or lost her job or just broke an engagement.

She may be a good girl. She may be a raving bitch. You don’t know. Be nice. Let her know she has toilet paper stuck to her shoe. She may be your next best friend. She may be a shoulder you cry on the next time the guy you’re dating decides he "isn’t ready to take it to the next level" or when one of your supposed best friends shatters the Girl Code.