premise: A man in a green shirt and dark pants and carrying a really big pot turns around to talk to 3 other people. hypothesis: Nobody has a shirt on.
contradiction: Nobody means zero people, but there is at least one person, the man, who has a shirt on.|contradiction: Either a man has a green shirt or nobody has a shirt.|contradiction: If a man is wearing a green shirt, then it's untrue that nobody has a shirt on.