Surprised nobody mentioned diaphragm punches yet, that could easily neutralize someone if you hit them hard enough.
Had the (dis)pleasure of experiencing that in a friendly duel a few years ago, fetal position followed shortly. At least that taught me where to punch someone in the future lol.

I’m surprised nobody said scooter to the ankle yet, that shit was painful af as a kid

Also anything to do with your fingernails hurts like crazy, and the recovery sucks, once I closed my car door onto my thumb and it hurt like crazyyy

It also sucks big time if you get any sort of cut on your lips, maybe it’s not the most painful initially but it’s crazy annoying. Any time you eat something, it stings. Any time you smile, it stings as well. Not mentioning how when it scabs you can’t do anything without feeling it pull.