premise: A man wearing a blue jacket fishing in a river having a conversation with his friend with no shirt. hypothesis: Guys at a campsite, building a fire.
contradiction: Guys cannot be one man.  A river is not a campsite and fishing is not building a fire.|contradiction: Fishing and building a fire can't be at the same time.|contradiction: You can't fish in a river and build a fire at a campsite at the same time.