You shouldn't steal food from a friend.
Dave and his friend Tony are at a restaurant, each with a plate of fries, when Tony gets up to go the bathroom.
Dave wants to eat another fry.
Dave grabs a fry off his own plate and eats it happily.
Dave grabs a fry off of Tony's plate so that he can get some bonus fries for himself.
Tony sees Dave eating fries from his own plate and is happy to see his friend enjoying himself.
Tony sees Dave eating from his plate and is angry his friend is so gluttonous.