Someone who aspires to be a ninja but never will because of their failing attempts, every time. They can also be referred to as a poser.
Johnny wanted to be a ninja but he couldn't due to his sucky ninjaness. All the little ninjas laughed at him and called him a ninjaring behind his back. Johnny was sad.
The act of tieing a black t-shirt around your head and pretending to be a ninja hiding behind walls from cars and climbing on buildings.
Im going to ninja the village and steal a prize from (insert name here)garden