The Pentagon is using RateBeer’s competitor Untappd to spy on people, so be warned, don’t go out drinking beer with any suspicious Iranians or North Koreans!
Overly social media is quite dangerous.
There is a Jack Ryan novel where a hacker combines hacking a relatively low level HR database and social media for a series of deadly assassinations. (e.g. they figure out who is important and find out more about you from social media).