Pistachios are a treat to eat, but they do take a little work. Most pistachios pop right open, but some can have very stubborn shells. That’s when I discovered it was time to fight fire with fire. Simply take a single half shell from another nut, and insert it in the gap between the stubborn nut’s shells. Then just twist the half shell like a screwdriver and the stubborn nut will easily open up and reward you with a tasty nut for your clever efforts.
Always do that, an it works like a charm.