Facebook Addict, often used on forums and facebook itself. Someone who, instead of "does other stuff then occasionally goes on Facebook" choses to "go on facebook then occasionally do other stuff.
Bill: Have you been on FB since I last logged in this morning?
Bob: Yeah, so?
Bill: You are such a FBA!
Bob: Yeah, so?
Bill: You are such a FBA!
by b1ue wat3r April 01, 2010