Wow, I have to admit, I totally love the creative way you think about killing testicles

I think you might need to tie the balls and fix them somehow, so they cant move away. Maybe you will have to push the beginning of the screw in the testicle first with some force, and then start rotating. I just fear there is no good wine comming out at the end, just some blood and sperm hehe

I just imagined how much damage you could do to a cock with that screw, because the cock already has an opening to push it in