Day 39 in The Beat Handbook: 100 Days of Kerouactions is titled, "On Nicknames," and references this passage from On The Road:
I remember my friends and I talking to each other in the 60s and prefacing comments with "Yo." Until I read this passage, I only thought of it as a way to get someone's attention, not as an appellation.
Anyway, I wonder where we picked up this particular language usage and whether it had some relationship to the beats.
Because, as you know, all roads lead to Kerouac.