system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that my testicles don't hurt during sex when they are smacking pretty hard, yet the lightest "ball tapping" from someone hurts like hell?
gpt
When you're aroused, your scrotum generally tightens up so your balls don't flop around as much. Also, someone else's taint is generally a lot softer than someone else's fist. Their chin, not so much, but your ball tapping mileage may vary.