How hard to you have to get hit in the nuts to make it cause permanent damage?

Some assholes in class were taking a hollow plastic pole and hitting people in the nuts with it. (Kinda like pushing the other end of the pole against guys nuts, not super quick tho) I got hit too and it it pretty bad. My nuts still hurt but I dont notice anything out of the oridinary. My mom just laughed, but I think getting hit in the nuts is not funny at all, infact it can be very serious, is this true though? How hard would you really havet o get hit?
Answer:
You're quite right. Make no mistake about it:
your "genitals" are the most sensitive area of
your entire body.
But, for someone to do irreparable damage
to your genitals, they would have to not just
hit them hard--upsetting the balance of your
so-called "balls"; they'd have to damage the
skin in a way that would actually cut open
that area, causing it to bleed.
That's not likely to happen, unless they were
to shove a knife into them.
By using a metal pipe, they could only bruise
the skin very badly. (But that part of your skin
is actually quite thick.)

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