My friend finds it funny to punch me in my nuts but it hurts me a lot when he does hit and he does it all most every day want should I do do make him stop hitting me there?

That person is not a friend. Tell him straight up to stop or you will not associate with him anymore.

Is there a reason you don't hit him in the nuts back... since he finds humor in your pain, maybe he can appreciate some of his own.

He seems like an a-hole to me. Give him some of his own medicine. Just tell him how it is and walk away. What makes him such a good friend that you would stick around to get hit in the nuts everyday?