An individual male or female who friend requests you and never posts anything on your wall after you add them. Also, a person who never even communicates with you on Facebook at all.
You add a person or persons as a friend to your Facebook friends list and afterwards never comments or communicates with you after being added. Once you identified such an individual or individuals that person or persons is now refered to as a Facebook Douche.
Someone who accepts your friend request, only to unfriend you a week or two later.
Jim: Hey, are you friends with Joe on facebook?
Bob: I think so, let me check...hey wait a minute, he unfriended me! What a facebook douche!
Noun: A giant douche-bag that enjoys posting feed after feed about his awesome life you wish you had. May possibly be, but not limited to, an over-muscular guy that has girls hanging off his eight pack who goes to every awesome party you weren't invited to, or an event you wish happened to you.
Daniel: Man, did you see Tim's post about hooking up with the hottest chick at that frat party?
John: Yeah! He also posted about that massive inheritence of 10 million from his dead aunt.
Daniel: He's such a Facebook Douche