premise: Boys and men, mostly all wearing helmets, hang on to two separate cars while they ride skateboards. hypothesis: The men are playing a game of baseball.
contradiction: You cannot play baseball and skateboard at the sametime because baseball is played in a field and skateboards will not roll on grass. Cars cannot be driven in a baseball field. In baseball only the batters and backstop will wear helmets so only just over half of the players will be wearing helmets which is less than mostly. Boys and men are different ages.