“97” or “Ninety-seven” (vegetable soup)

 
Newspapers.com
10 August 1941, Atlanta (GA) Constitution, “The Code that Speeds Soda Fountain Service” by Yolande Gwin, Magazine, sec. D, pg. 5, col. 7:
Vegetable soup, termed as “97,” maybe because it contains 57 varieties with 40 more thrown in for good measure, according to one clerk, while another term applied to soup is “heavy.”