1. Synonymous with terrific, but carrying extra weight due to the addition of the word ninja because ninja are supremely terrific already.
2. Terrific in a ninja kind of way.
3. Ninja + Terrific = Ninjarific
2. Your cosplay outfit is ninjarific!
3. That anime is super ninjarific!*
*Note: in this instance it can mean that the anime involved ninjas and was therefore terrific in it's ninjafulness.