How do I get the "Ow My Balls!" achievement?

Solution 1:

So I did a bunch of testing on this tonight. This is what I have found:

• The nutshot and the testicle assault do not have to be done on the same enemy. The achievement simply pops after you have done each activity the first time. I killed a gang member via testicular assault without doing a nutshot on him and acquired the achievement.

• You need to actually kill the enemy via testicular assault in order to get the achievement. You'll know when you have done this because you'll see a popup for Respect with the name Testicular Manslaughter. Hitting an enemy twice with a testicular assault will get this done.

• It does have to be done on a male character. I tried doing testicular assaults on female gang members, and while I was able to kill them and they did the animation, I did not get credit for a Testicular Manslaughter.

Solution 2:

I got this one by:

• Shooting someone in the nuts with a pistol (thereby causing them to grab their nuts)
• Hitting them with the testicular assault, which killed them

I did this on a male rival gang member, I don't know if that was important or not.

I don't know if this is the only way to unlock it, but this is how it popped for me.