Ninja:
A rather confused individual who likes sneaking around at night in his pajamas.
Ninjutsu:
The art of being confused and sneaking around in your pajamas

Ninjas... Everybody's favorite plot devices! If your story or game's getting dull, just throw in a few well-placed plot-ninjas and everyone will have a good time, guaranteed! I've gotten into the habit of saying "And suddenly... ninjas!" either whenever the conversations have turned stagnant, we need a laugh, or just because every has such funny reactions at the randomness.

I so want to make this a t-shirt.