An add-on that signifies that something is really badass, dangerous, or hardcore and might seriously fuck you up.
Yosef: "Check out this awesome gat I've got. I think I'm gonna go to the ghetto and shoot someone!"
Abraham: "That's a BB gun, dude. It probably won't even break the skin."
Yosef: "Whatever, man. It's the BB gun of DOOM! It could kill you, seriously. Watch out!"
Abraham: "You just shot me, you fucking idiot! That left a mark...oh, no wait, it's gone."