A recent New York Times Magazine piece focused on the expression "you do you" (and its variant "do you"), meaning something like a strong affirmation to "be yourself."
The article associates the phrase with a narcissistic "millennial" culture, implying that it has become popular very recently. Regarding its etymology, the author only asserts: "'Do you' certainly sallies forth from black vernacular, even if the nature of its mundane parts makes its origin Google-proof," which sounds like an appropriate challenge for this forum.
Some comments on this article have posited that the phrase and usage is older, at least dating to the 1990s. Any thoughts on etymology or history would be welcome.