Because they are tenuously sensitive.
large amounts of nerves and pressure in the testicals. It hurts when any body organ is hit, like the kidneys.
Because that’s your bodies defense mechanism to protect the future babies you may have. So if it hurts, then you wont bang them, and if you continue to bang them it resultsin decrease sperm count, or other health problems.
God made it that way so women can stop a rapist’s action by a single kick and render him invalid.
There are many nerves and nothing to protect you.Make sure you protect yourself well because if you get hit there hard enough it could cause you to not be able to produce sperm.The same can happen if you wear extremely tight pants or leave a laptop on your lap too long.How do I know this?You dont want to know.