Pets just know. My dog can hear the crinkle of a potato chip bag the minute I put my hands on it, and by the time the bag starts tearing, he’s right at my feet, tongue hanging out, anticipating the coming feast. I guess it must be something in that material they use to contain junk food, it’s usually quite noisy to the touch, which makes it the perfect alarm for any alert four-legged gourmand within earshot.