I bought some new boxers a while back, noting the main selling point on the packaging.
"Improved design prevents gapping!"
I'd never read or heard the term "gapping" before -- not as it applied to underwear, at least. Still, I immediately understood what "gapping" must be, and immediately wished to eliminate "gapping" from my life, via these new boxers.
So, given the effectiveness of this marketing, is it possible that the term "gapping" was actually coined by advertising wizards? Perhaps these executives chose this word after rejecting others, such as "flopping"?