vulgarity gap
n. A disparity in the tolerance for vulgarity between generations or communities.
Then there’s the matter of the so-called "vulgarity gap." It has become a cliché to posit that millennials/Generation Y have an ease with crudeness that distinguishes them from their parents’ generation.
—John Doyle, “TV trend alert: young people mocking older people,” The Globe and Mail, September 17, 2013
Nothing dates a Boomer so fast as to wince at expletives and vulgar humor. Yet a quick look at Adult Swim, Family Guy, and quickly show that Millennials are perfectly comfortable with language and humor that makes my generation blush.
—“Millennial Marketing: The Vulgarity Gap,” Millennial Marketing, March 27, 2009
2007 (earliest)
I live in the US and I occasionally discuss about the huge "vulgarity gap" between Italian and American. Things that in English are quite vulgar, are not so gross in Italian.
—Giulano Casale, “V-day: Instructions,” Beppe Grillo's Blog, August 10, 2007