There’s two ranges where a groin kick works: close and mid-range.
Say someone grabs you face to face, or pins you to the wall, and your hands are blocked.
Now you’re close-range. What do you do?
You come in closer, as close as you can, and with every ounce of adrenaline and aggression in your body, you do a can-can kick.
You know the first step in the can-can, where you raise your knee up as high as it’ll go as strong as you can?
Do that, as hard as you can, repeatedly.
If that doesn’t work, here’s the alternative. You’re going to take your hand, grasp between the thighs underhand. Its going to feel like you’re “cradling” the testicles. Dig your fingertips into the fragile skin BEHIND the scrotum. Then, once you have a good grip, you turn your hand into a vise, with your fingers digging inwards to the material. If you do it right, you should feel the testes INSIDE the scrotum. You want, whenever possible, to hook your fingers under them.
Then, with your hands in a claw and your fingertips latched behind the testes, you turn your hand sharply, as though you were turning a doorknob. Simultaneously, haul your elbow back and up as hard as you can.
If done properly, this technique can tear the scrotal tissue, and done with enough force, can tear the testes out of your attacker’s body.
No matter HOW pissed he is, he’s gonna drop. I’ve tried this technique on guys wearing cups and even with protection, it is not a fun feeling.
If you’re mid-range and have enough room for a kick, the goal becomes to use your shin.
The shin is actually called the tibia, which ounce for ounce is one of the strongest bones in your body. So, here’s what you do, my little bloodthirsty beaus:
You aim, you scream “DO NOT COME CLOSER I SAID NO!” (legal purposes, because now you’re officially exercising your right to self-defence). Maintain a 360 degree awareness, just in case he has friends, and then, when he’s close enough, connect your shin full on soccer kick with the delicate squish of his testicles.
What you want is as much upwards force as possible in combination with as much momentum as you can manage. When he collapses, which he will, then stomp on his groin again, and then run.
The latter has less of a trick to it. It’s primarily about momentum and force.
Remember, if you’re close enough to put your hands on him, use your knee. If he’s coming at you, use your shin.
via How to Kick a Guy in the Balls: An Illustrated Guide.