Definition: A signature that is "scribbled".
Everyone knows someone with a scribnature. It wouldn't surprise me if most people have one. I do. Athletes do. Doctors obviously do. A scribnature is easily identifiable; it is nothing more that a glorified scribble with perhaps one or two obvious letters. I always thought the were cool as a little kid. And I spent forever to perfect my own. I guess we just use scribnatures because they're faster to write. And, of course, way cooler than normal cursive.