noun: An intentionally vague or one-worded status update, alluding to something else. This could be an inside joke, or anything meant for only a few people. More simply, it could be a plea for someone to comment. Such as "pointless", "frustrated", or any inside joke.
Did you see Jeremy's vaguebook? All it said was 'pointless'.
To seek sympathy and/or attention by posting something vague as your Facebook status. Usually the only people who ask you "What's wrong??" are lonely stay-at-home moms who want some extra gossip. The rest of the free world does not give a shit and wish you would just suck it up and shut the fuck up.