Facebook Knows Where You've Been and Is Using It to Suggest Friends

— -- If that guy who popped up in your Facebook "people you may know" section looks vaguely familiar, it may be because you've recently crossed paths.

The section is usually a trove of high school acquaintances and a random assortment of colleagues with whom you have mutual friends, but Facebook also suggests friends with whom your common link may be unclear.

It turns out what two people may have in common is a shared GPS data point on their phones. Fusion first reported the story after a parent who attended a gathering for suicidal teens said Facebook suggested he friend another parent who attended -- despite having never shared any information with each other.

Facebook did not immediately respond to ABC News' request for comment. However, a company representative told Fusion that location is just one factor in the algorithm the company uses to populate the "people you may know" section and that the two parents must have also had something else in common.

How to Turn Off Location Settings

While the super-smart algorithm may come in handy for networking with people you met at a party, you don't have to use it. Android users can visit their app manager to open Facebook permissions. From there, toggle location to "off."

People using an iPhone can turn off location services by going to settings, privacy, location services. Scroll down to Facebook and choose "Never." It's also a great time to evaluate the location settings on your other apps.