The title screen for Kickle Cubicle is nothing to write home about.

But if you plug in a second controller and hold down its A Button while you turn your NES on, and then keep on holding it until the title screen shows up, you'll notice that the little blue thing has been replaced by a certain Radical Ninja

He doesn't actually affect anything else so far as I can tell, but I bet you didn't know he was in there.