Is there a training excercise that my partner can undertake to learn to handle my testicles with the proper amount of force?

I told her that they are about as sensitive as eyeballs, which is sort of true, and since we both have eyes, I thought she would get it. She is still a little careless though.

I enjoy the overall process of having my testicles manipulated because it allows me to put my trust in my partner and surrender to her, which is what I am into.

It also feels good. Except when it doesn't.