James Burnett, perhaps the blogosphere’s most eminent authority and critique on etiquette decided to address a growing concern among his female readers,
“I have gotten a number of requests from female readers that I write something about the bad manners that go along with men grabbing their goodie bags in public.
[…]
Some men grab/touch their nether regions in public because they get an itch or because the contents of the package have shifted during travel and need to be put back in place. Sorry, blunt but true.”
The thing about “Icles”, James Burnett
So go read his post. You know you want to. James manages to come up with an acceptable compromise for both the ladies and the gentlemen, akin to a rule-of-thumb you might have picked up in elementary school.