that would be an old wives tale.

Still I have kicked people in the nuts but I haven't ever had the favour returned to me, worst thing I ever did involving someone's nuts was when my mate was on drugs and being an ass. He had a prince albert piercing and all knew this, so myself and 3 mates came up around him, grabbed his boxers by the waist band and lifted, he was off the floor by about half a meter dangling from his boxers untill they physically ripped over his head and dropped him on the floor.