heres an original idea:
im a firm believer that cock and balls shouldnt ever come into the situation because frankly they are so important i dont even think rapists shoudl have em broken off, but if you want to scare the fuck out of him and make him stop, pick him up, throw him down and since ur prolly so much bigger than him, tie him up, rubber band around the nuts, holding a knife right there,(fightclub style) tell him exactly whats up, and give him a week to get the fuck out of the area or to shape up