“If you told someone with a penis that you were going to scratch, slap, or tie up their genitals, chances are, they’d recoil at the mere thought of the pain. But, there are also people out there who wouldn’t just withstand that agony; they’d love it. They enjoy a kink based on this specific kind of pleasure: cock-and-ball torture (CBT)…”

link: http://www.refinery29.com/cock-and-ball-torture-cbt-meaning