In Have Space Suit--Will Travel, by Robert Heinlein, the POV character Kip says, after spending some time immobilized in an alien hospital:
There was a mirror ... It showed me with enough hair to warrant a guitar (I wear a crew cut) but somebody had shaved me. (end of ch. 9; p. 192 in 1977 Ballantine mass-market paperback edition)
We just had a bunch of discussion in the media of the 50th anniversary of the Beatles' 1964 appearance on the Ed Sullivan show, and from the reactions in 1964, it seems like their haircuts were considered outlandish. People were apparently selling Beatles wigs, which implies that the style was so new that teenagers hadn't yet had time to grow out their hair naturally. What's up, then, with Kip's reaction, in a story written in 1958? E.g., in old photos of Elvis from the 50's, he has a DA, but not long hair like what was popular in the 60's and 70's in the US.