As much as we would like to take credit for inventing the Beer Milkshake, the first reference we have found is in Steinbeck's Cannery Row.
"Henri watches a pole skater hired by Holman's Department Store. Doc heads for La Jolla. Eats a hamburger at Herman's, then more at Gonzales, King City, Paso Robles, Santa Maria and Santa Barbara where he picks up a hitchhiker whom he throws out at Ventura where he has a beer milkshake."
and
Blaisdell poet who proposed the beer milkshake
