Apparently, you can use Facebook to tell if someone's popular . . . or a self-absorbed, self-righteous narcissist.  Just check if they have more than 800 Facebook friends.

A study out of Western Illinois University from Globe and Mail found a link between the number of Facebook friends a person has, and the potential for a narcissistic personality.

The cutoff seemed to be around 800 friends.  People who had more than that exhibited stronger signs of self-absorption, vanity, superiority, self-importance, and aggressive responses to negative comments than people who had less friends.

People with more than 800 friends were also more likely to change their profile photos regularly and disclose more personal information.