Testicle Skewering
From BME Encyclopedia
Testicle skewering is a form of ball torture that involves temporarily piercing one or both testicles all the way through, from one side to the other, usually with a hypodermic needle, a longer spinal needle, or even just a simple sharpened skewer. It is important to note that it is very easy for an infection to fester and grow inside the scrotum, so extreme care should be taken to ensure that all play is sterile.
Many more pictures of this type of play can be found in BME/HARD.