"Social" media means those forms of communication which are, actually ...
... antisocial !
So, if you facebook your friends, instead of actually talking to them, you are using "social" media.
If you are with one group of friends, and you rudely start using your phone to communicate with another group of friends, you are using "social" media.
If you are on a night out, and you ignore the people you are with so that you can post pictures on your Facebook page of the "great time you are having", you are using social media.
Etc ...
In fact, in essence, if you are being rude and antisocial, and an electronic device is involved ... then you are probably using "social" media.