I'm going to have to call bullshido on this one:
I've been kicked in the ol' rod & tackle before- while wearing a groin cup, no less. I'm not going to lie. It HURTS. On a level that no man should EVER have to experience.
So I'm more than a little sceptical when I see guys simply taking shots to the nuts without so much as flinching. To me, the maths there just doesn't add up.
Moral of the story is, don't take on martial arts training that tells you that you can simply learn to ignore and overcome pain without any consequences from taking massive hits to vulnerable extremities. You are far more likely to end up curled into the foetal position screaming on the ground than you are to impress your would-be attacker with your manly manliness.
And then, of course, there is the small matter of fathering children afterward, which (as far as I am concerned, anyway) will likely prove troublesome if you do what is touted above.