I read in an old vietnam book or something that while under fire a guy got so scared that his nuts retracted back to the area they were in before he hit puberty. I believe he had to get surgery to pull them back down. When I start getting really scared (man with a gun, shots fired, barricaded suspect) i just keep telling myself to expect the unexpected.... the ball retraction is the first thing that comes to my head.....and then its getting shot