An acronym mean Face Book Material. When one believes that a picture taken is ether worthy of being your default picture or the cover picture of a Photo Album.
Wow Jim that picture I took of you last night passed out on Nicks crotch is hilarious; its FBM to say the least.
Fleet Ballistic Missile Submarine. An acronym used to describe a submarine launched ballistic nuclear missile carrying submarine or "boomer". The United States currently operates these in the form of the Ohio Class.
Jimmy is the captain of the FBM USS Louisiana. He could blow up the whole world if he wanted to.