Dead arm

How is it that women know just where to hit a man's arm to cause it to go numb and be very uncomfortable?

Is it something they teach you in school when they send the boys out to play football so they can talk to the girls about periods and then use any time at the end to throw in a few useful things like dead arms and manipulation?

My Wife is the master of the dead arm but as usual I was the innocent party. She was commenting how one of my armpits creates a lot more sweat than the other and when I pointed out the huge spot on her forehead to deflect attention from me she administered the shot in the arm asking "why would you say such a thing?". Because it nearly had my eye out that's why!

Then she tries telling me that another whack in the exact same spot will miraculously take the pain away.

I may have been born at night love, but it wasn't last night. Nice try!