FaceBomber (feys bom-er) -noun One who makes random comments on their friend's Facebook pages, or those they don't actually know or remember but accepted them anyways, often after extremely long periods of time since you actually communicated directly with them but you forget because you read their posts in your feed everyday and you feel like you know them again. see also PhotoBomber
This guy is such a Facebomber, I haven't spoken to him since high school and he keeps making stupid comments on my wall.
One who "bombs" your Facebook News Feed with multiple status updates, link/video posts, picture uploads, Foursquare check-ins, etc. Basically someone with no life.
I know all the details of Ryan's day, including his bathroom breaks, because he is a FaceBomber.