I've never understood the motivation for a big swingin' sack heh. Don't you think its going to be awkward during sex with it flopping around? Could get painful...
Hell yah, get that lady in a doggy style position and let your balls start bouncing off her clit and watch what happens. Or flip her over and let them slap her butthole for a few times. It lights them up!!
Or...just rub your sack all over their face. Don't ask me why, but not only have I had woman beg me to do this, but I've tried this move on a couple of more 'conservative' girls and they've gone through the roof as well.
Whatever floats the ladies boat is good in my book.