Letterman: The Last Giant of Late Night by Jason Zinoman:
More than any other comedy figure, Letterman redefined countercultural cool as knowing, square, and disengaged. Authenticity, the currency of cool for ages, was out; only a fool still believed it existed. What mattered was signaling that you knew it. You saw this clash of old and new styles play out when the pop star Billy Idol appeared as a guest on Late Night.
Idol adopted a glossy version of Sex Pistols style with all the usual signifiers of a punk rock aesthetic: black leather jacket, shock of white spiky hair, a scowl. Idol told Letterman that his songs were so popular that drug dealers were naming their products after them. Instead of chuckling merrily or changing the subject, Letterman injected some antagonism into the exchange and sneered, “You must be a very proud young man.”