How to get kicked in the nuts
One thing that can help, and never hurts, is to get to know a large number of women. You can find out about things like, yanno, how they think by doing a lot of listening. If you meet a large number of women, it is very likely that you will eventually come across one who either brags about having racked a guy just recently or who saw a friend do it and thought it was cool.
Zero in on the ones who recently racked a guy or seem to like seeing guys getting racked. (I was watching a Hong Kong flick and Jackie Chan kicks some guy in the balls during a fight and this chick I was with cheered - and I says to myself, "Got one!!! THANK YOU, God!")
Women who are into ballbusting are often more shy about talking about it than men are -- and men tend to be pretty shy on the subject. Once you have met a large number of women and once you have figured out which ones seem to be into busting, hang out with the busters. If they ever bring up the topic of having racked a guy (or cheer in a movie when a guy gets hit in the 'nads), the way is open to start sharing ball-kicking stories. Let nature follow its course. :D
Another thing is to court many female friends (as friends, not as sex toys, which, other than ballbusting, is the only known use for women). With friends -- you can argue sometimes. If you are like me, you have many a Neanderthal opinion that is guaranteed to start fights. My recommendation is to work in becomming friends with feminists -- and the more FemiNazi, the better! Argue with them about something related to men and women and innate characteristics, and let your opinion slip that women are whores.
Also, meeting women is often done at parties and bars and such -- this is a great venue in itself for getting a knee between your legs if you are enough of a jerk. They are also great venues for making friends with females, because most of the chicks will be sick of guys hitting on them for sex -- since you are not looking for sex, you can work on making friends, to later be transformed (one hopes) into a nut-kicking bitch of a friend.
The worst thing that could happen is that you might accidntally just make a friend. Gee, that would suck, right? ;)
If all else fails, these ingredients generally do the trick:
A female, preferably one not quite right in the head
Liquor or some other intoxicant
A repetoire of smart-ass comments
You dumped a girl that was ball busting you?
I suppose helping you out with your sexual fantasy isn't EVERYTHING in a relationship. I bet if you have an experienced g/f who busts your balls it is REALLY difficult to replace THAT part of her when you move on to your next g/f!