What is a guinea pig thinking?
Shrieking because the fridge opened. That is the whole reason.
The noise has a name. It's called wheeking, and it is not a sound guinea pigs make at each other in the wild — it is one they developed specifically for humans, in the same way cats invented the meow for us. A domestic guinea pig learns, fast, that a particular noise produces a particular human, carrying vegetables.
The fridge detail is the giveaway. They are not reacting to food. They are reacting to the SOUND that has historically preceded food, which means the animal has built a working model of your kitchen habits and is now operating it.
Try it on a real one
Three peeks a day, free. No account, nothing to install.