Facebook spent years defining what it means to have an online identity. Now with the surge in popularity of anonymous social apps, Facebook may be spending next few figuring out how to deal with the complete opposite case. The social networking giant has expressed interest in exploring how it can develop anonymity services. Secret, one of the latest buzzy social apps, has met with Facebook to discuss how the two companies can work together, according to people familiar with the matter. Details of these discussions were not available and both Facebook and Secret representatives declined to comment on this. Rumors of a $100 million offer from Facebook to buy Secret that reverberated through Silicon Valley this week were shot down by two people familiar with the social networking giant’s plans.