A group of people who are not blood relations listed on facebook profile as a member of your immediate family (e.g. mother (facemum), father (facedad), brother (facebro) or sister (facesis).)
Charlie: You're pretty close with Fin, aren't you?
Adam: Yeah, he's one of my best friends and a facebro.
Dan: I didn't know you had a brother, dude.
Josh: Oh, lol, I don't really. That guy's just part of my facefamily. None of my real family actually has facebook!