I saw a video where crows in England would drop nuts on the street so cars would run them over to crack them open. Then, they realized that it was dangerous to pick it up (with cars and all). They noticed humans could walk in crosswalks when the light changed, so they realized that they could drop them in the crosswalks, cars would run them over and crack them, and then when the light changed, they would pick it up and not have to worry about getting hit by a car. That's seriously pretty damn smart for an animal