premise: Two men in costumes with fake carrot noses, top hats, sunglasses and white fur coats that contain white electrical lights. hypothesis: Nobody has a costume one.
contradiction: It cannot be both that two men are in costumes and nobody has a costume on.|contradiction: If two men are in costumes then somebody has a costume. Nobody implies that no one has a costume.|contradiction: Two men cannot be in costumes when nobody has costume on.