A Pinja is a person who has the best of both worlds, such that they are squeaky clean and stealthy like a Ninja, but are also flashily dressed and able to drink a lot like a Pirate.
Pinjas do not inhibit the bad traits of either of these such as being eaten by a Kracken or being shot by a gun ... thus, they are both better and superior to both Pirates and Ninjas.
Jim: That guy just shot me and stabbed me with his sword at the same time. His breath smelled like rum, it must have been a pinja.
Ben: A pinja? you mean a pirate and a ninja crossed? but the best of both?
Jim: Exactly. Lets go to some strikeouts.