Obscenities:

Whyvert (Twitter):

The rise of antinomianism (breaking norms to assert status). E.g. breaking the norm against swearing marks you as cool. Before the 1970s books had virtually no swear words. Now they have lots. Tattoos assert status as cool and sexy by breaking fuddy-duddy norms.

Use of obscenities in books may have started in the 70s, but greatly accelerated in the 2000s, in line with the recent rise in tattooing.

Profanity in popular music lyrics, virtually non-existent until the 1990s and 2000s.

Antinomianism (as measured by the rise of published profanity in the last 20-30 years) is both a lower human capital (pop music) and upper human capital (books) thing.