I had a gay friend that would put a ball separator on me then attach a small chain to my balls. Once i got my cock in his ass he'd put a LOT of tension on the chain and, hence, on my balls. It was the kind of think that hurt really good. It would make me cum so much harder.
He'd also put a cock ring/ball separator on my balls, attach a very heavy lead weight and a small chain. He'd pull me arraign by my balls, every now and then jerking on the chain. Jerking on the chain would cause the weight to yank on my balls. Also the kind of thing that hurt really good.
I'm pretty sure there are a lot of guys out there that like this sort of thing.