So Bob92,
There are several theories about Michelangelo’s David. The one I think most likely is that Michelangelo followed the Greek tradition of preferring a smaller manhood. A large one was often a sign of being stupid or bestial in Greek society. The second one is based on anatomy, which Michelangelo was a master. The manhood will shrink and withdraw, along with the scrotum during times of stress. They are getting ready for the flight or fight.