A term regarding most of the Call of Duties, especially Black Ops. A magic bullet is the last bullet in a guns clip, which ALWAYS kills a person (the magic bullet is shot and then reloading follows). Even if if the person barely shot you, if you get hit with the magic bullet you die.
DUDEE!!! WTF I was owning this dude and then he got me with his magic bullet! What a lucky douchebag!