Advice for son, women only?

As I asked before, I wasnt sure how to talk to my son/ force him to wear a cup while playing baseball. He just doesnt believe that getting hit with a baseball with hurt him. What I think is he has never been hit "down there" before. Should I maybe give him a accdintaly tap in his to show him how painfull it is then explain what a hard baseball could do. Or is that to much. any other suggestions? And talking to the coach didnt work.