Warning! This is a video made by a straight guy for straight guys, because us gay guys already know how to do this. It's by being in a public place that doesn't mind some self crotch action, like a leather bar, Home Depot, or the Grand Ole Opry.
But if you or a loved one needs a lesson, enjoy! BTW, will someone please make a video on how to adjust your balls in private? Oh wait, I think you can find leads on some of those here on GayDemon.