premise: Three men are doing a musical set with wires and equipment all over the stage, and they are holding unique guitar like instruments. hypothesis: The three men were telling jokes on stage to entertain the crowd.
contradiction: The men can't be doing a musical set while telling jokes.|contradiction: The men are either telling jokes, or doing a musical set with their guitar like instruments.  These are not usually the same thing.|contradiction: either the men are telling the jokes or doing musical set.  both cannot be done at the same time.