Have you ever thought about how stupid is to have your testicles hanging down there ?

Consider:
  1. They stick to your legs when you sweat
  2. They are easily kicked or otherwise damaged
  3. They are suspended by a weak ligament (plus assorted tubing) that can stretch, get inflamed and lead to all sorts of grief.

Now, a physiologist will say "Sure, but they have to be there because if the temperature is beyond 34 Celsius the spermatozoids die". Now, this is like saying that Windows crashes because otherwise the BSOD would have no purpose and little Billy from Family Circus, the BSOD programmer, would cry: kind of ass-backwards if you ask me.

If you had to design balls, would you not put them behind a nice thick bone, or at least deep in the body, like ovaries?

But no, there they are, your only hope of reproduction (or rather, your only two hopes thereof), exposed to a cruel, ball-eating world.

On the other hand, balls are hardly unique: the gallbladder, the appendix, and the thymus (whose only function in your adult life is to get cancerous) share with balls the dubious honour of being more trouble than necessary.