One day you come home and your dog is barking and snarling at you like you’re some kind of threat. You say, “Chill, Dog. It’s me. You licked pizza grease off my fingers last week.” But she won’t listen. She keeps barking and running around the couch, chest out, teeth bared. “What the hell, Dog?” you plead, kneeling down and taking off your hat. This subtle change in appearance elicits a sudden response from the dog, who runs up to you with her tongue hanging out and her tail wagging. “See, you remember me,” you say as you put your hat back on to pet her. She freaks out again. Take the hat off and you’re a friend; put it on and you’re an enemy. At some point, some dude in a trucker cap must’ve done something nasty to the pup, and the poor thing made a sweeping but false generalization about what happens when a human puts a hat on his head.