The purpose of a ninja...

Is to flip out and kill people.

Anyway, I am reminded of this after my last combat in Kingdom of Loathing:

You're fighting a Demoninja

A big red ninja with horns stands before you.

"I am the Demoninja," he says. "Allow me to demonstrate the myriad ways in which I can whoop your ass."

He gets the jump on you.

He tries to ninja you in the head, but misses.