I have used cock rings around my balls of various sizes. Have stacked multiple rings to stretch out my scrotum. Have vacuum pumped them as well. Dripped candle wax on them. But the hottest thing I've done is nail my scrotum, not the balls, to a board. Started out with push pins and cardboard. That was fun, delightfully painful, but fun. I progressed to finish nails and wood, driving the nails with a hammer. It sounds like it would be extremely painful but it wasn't. It did hurt, but not that much. First time I orgasmed without stroking! I have done this several times now. The last time I used 12 nails.
