We did one called "Removing the Jewels". If someone has you in a headlock from the side, you drop down into a low horse, palm strike accross your body into the abdomen, followed by another palm strike with the same hand to the groin. For decency's sake they didn't really go too far in depth, but I got the idea.. When you meet your mark, squeeze and pull back with force. I suspect tight jeans might limit its effectiveness.
What I've noticed, and of course my knowledge is rather limited, groin attacks were always done with the hands, rather than going for a kick squeh in the nads.