A sad creature whose sole reason to exist is to bombard others with SMS'.
These people has no social network except their SMS "friends", and will never actually answer the phone if you try to call them, but wait five minutes, then resume their messaging.
Not necessarily gender specific.

Internet persona(s) who happens to follow you and you happen to follow them back and maintain communication with and have a mutual liking for eachother whether it be friendship wise, etc. (Mutuals if more than one mutual)