Feeding habits of the common ninja

When feeding ninja, keep in mind that they need to take off their masks to be able to properly eat.

Also keep in mind that ninja can turn anything into a deadly weapon (assuming they don't use the various deadly weapons they carry).

Finally, keep in mind that if you see a ninja's face, the ninja must kill you.

So, the moral of the story: don't feed ninja. Pray they're distracted by other ninja.

Or pirates.

Or robots.

Your best bet is robots.