GIRLS ONLY: Is it fair to go for the balls in a fight against a guy?

I was play wrestling with my boyfriend the other night and I grabbed his balls and gave him a light squeeze. Nothing to cause harm or a severe pain, but enough for him to let me go and grab his groin. I was of course able to get on top of him and do what I wish. He said, that I cheated. I think that it is not cheating. Just like he got bigger muscles is his advantage, his balls are my advantage. What do you think?