Dont know the rules in MMA for this and its not exactly PP but it hurt. Knew a guy used to randomly workout w/ the MMA guys we rented mat space to and I was learning from them. This guy went to georgia for cage matches and I was told was no slouch, bad thing though...he (no lie) wore a steel cup that must have been a little pointed, he used it to work inguinal PP and if he was in the position for it would use it on your sternum (The Sternum knuckle rub replaced the ear lobe pinch to rouse the passed out drunkards in EMT and Police work if I recall correctly).
Its probably not cool in a match, at least the guys I was working out with warned me ahead of time but I sucked comparatively and tapped when the sternum felt like I was being cut open.
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