I actually just recently, after years of frustration, figured out a technique that works. You squeeze the box near the opening so that it bulges out. Then you can poke it with your finger and rip the top open. Feels like gutting a fish, which I assume now is what they were going for.
dude, wtf? That literally happened to me today. I was bringing my kid a bowl of strawberries when I stepped right on top of a little toy house. Me on the floor. Strawberries all over the place. And all my kid could say was "wow, that was scary," and then went back to playing. Savage.