Sorry but slightly off topic, but still on the topic of balls:
A friend told me recently that in a past encounter a guy had pulled on his balls so much that it caused an injury. My friend had to stay off sex for a month while it healed, and after that, he could feel the scar inside on his sac, around his vesicles. But he said the sensation slowly became more and more erotic and now he can get off just caressing and manipulating that part of his scrotum where the scar tissue is. (The injury happened before COVID).