It turns out that high school hallways aren't the only places mean girls exist.

Twenty seven percent of American workers report being bullied at some point in their career, according to the Workplace Bullying Institute (WBI), and women are the biggest offenders.  The WBI report found that women bullied other women 68 percent of the time; sometimes the bullying came in the form of outright harassment, but other times it was more subtle.

Many of you have experienced working with people who claim to be your friend, but then turn around and make belittling comments or roll their eyes at you in front of fellow colleagues.  This type of relationship can undermine your productivity, reputation and mood at work.

Here are four tips from etiquette expert Jodi R.R. Smith., author of The Etiquette Book: A Complete Guide to Modern Manners, that will help you deal with a workplace 'frenemy' so they don't succeed in sabotaging you. 

   1. Know your frenemy - It's to your advantage to identify your frenemies and be wary of their motives -- all while remaining professional on your own terms.  "Once you know what type of person your colleague is, you can take action as appropriate," Smith says. "Know what you can expect from them, when you can rely on them and when you should not."  Even if you're wary of this 'friend,' don't completely ignore her. Knowing her moves and motives can keep you one step ahead. 

   2. Create boundaries - Remember that work is just that... work. When possible keep personal issues out of the workplace, even if your colleagues don't reciprocate. In other words, try not to stoop to their level. "Take the high road and don't lose focus on your own hard work," Smith advises. 

   3. Be honest when necessary - Playing the diplomat isn't always possible, especially if a frenemy clearly crosses a workplace line. Feelings of tension can also hinder productivity for both parties, so it can be helpful to clear the air. "On occasion, a frank conversation can aid your relationship," Smith says. "It's OK to say, 'We're never going to be best friends, but I respect your work and hope that when we're on the same team we work past our differences to get the job done.'"

   4. Know when to walk away - Savvy workers know how to balance the good and bad of the workplace environment to their advantage, but even the thickest-skinned have a limit. It's a given that there's always going to be someone you don't like at work. "However, when there are many office frenemies, there's only so much emotional stress you can take before it's time to dust off the resume and look for a healthier work environment," Smith suggests.

Frenemy is not a made up word.

In 2009 it was added to the dictionary. It means one who pretends to be a friend but is actually an enemy. 

These days a lot of the workplace bullying is done by frenemies.