The scrotum is the sac, not the balls. You’d need to be aiming for the testes, were the OP correct.
That said, speaking from recent experience, precision isn’t a priority in this situation. Penis, scrotum, testicles, balls, nads, vas deferens, foreskin, third pubic hair on the right and straight on 'til morning, as long as you manage to miss the quads and the bones and hit something soft very hard you’re golden. Nomenclature is for later.
I don’t recommend kicks, as we tend to see them coming. The USMC apparently used to recommend “grab, squeeze, and twist IN A VIOLENT AND FORCEFUL MANNER”, which, given the capitalization, makes me wonder how many were grabbing, squeezing, and twisting in a gentle and sensuous manner. That will often make a fellah let go, but not always. Sometimes it gets complicated.
I prefer “Naughty Bits”, as it seems fairly universal and fun.