According to a study conducted at Washington State University in Vancouver, gossip is a form of sociological warfare used to damage the reputations of competitors. Anyone who has survived 7th grade could tell you that!
According to Nicole Hess, who authored the study, participants were more likely to trash talk competitors when raises or promotions were at stake. The trash talking was lowered, however, when the competitor had an "ally" in the company, as having a friend "in the know" helps targets of gossip thwart vicious attacks. Both sexes gossip equally, says Hess, but according to Kate Wong of Scientific American, "women more often than men find themselves in situations in which gossiping pays off."
In other words, having a friend at work can help you fight off vicious rumors and attempts to destroy your reputation. It's hard for your competitors to tear you down when there are friendly voices refuting the misinformation they're attempting to spread. Unless you're friends with Regina George, and then you should probably start looking for another job. Especially if your job entails trying to make "fetch" happen. It's NOT going to happen.
Pssst: Gossip Hurts—But Friends Can Protect You From The Worst Of It [Scientific American]