Entry in progress—B.P.
 
“hash house lingo”
 
Google Books
Cassell’s Dictionary of Slang
By Jonathon Green
London: Cassell
2006
Pg. 684:
hash-house Greek n. [20C+](US) the jargon of US fast-food restaurants and cafes [HASH-HOUSE n. (1)+GREEK n.; such jargon included SLAUGHTER IN THE PAN n., RED MIKE AND (A BUNCH OF) VIOLETS n., two of a kind, fishballs and a sheeny funeral with two on horseback, roast pork and boiled potatoes]
     
Google Books
The American Thesaurus of Slang, with supplement:
A complete reference book of colloquial speech
By Lester V. Berrey and Melvin Van den Bark
New York, NY: Crowell
1948
Pg. 202:
...hash-house Greek, lunch stand jargon;...
   
5 September 1971, New York (NY) Times, pg. XX1:
The Traveler’s Guide
To Hash-House Greek
By DAN CARLINSKY
(...)
So in your own country—where, if you expect to do any traveling, you run the risk of getting stuck in a diner at some time and place—you owe it to yourself to learn Hash House Grek, the peculiar American lunch-counter cant.
 
How else will you comprehend “stretch one and let it bleed”? or “hold the cow”? How else would you know that to order submarine sandwiches (those grand concoctions of onions, sandwich meat, cheese, lettuce, tomatoes, oregano and oil served on a long roll) you must ask for hoagies in Birmingham, grinders in Hartford, heros in New York, poor boys in New Orleans, rockets in Cheyenne, torpedoes in San Diego, Italian sandwiches in Louisville, and Cuban sandwiches in Miami.
 
March 1977, Yankee, pp. 86-97:
Hash House Greek Spoken Here
By Douglas Yorke and Eve Yorke
 
Google News Archive
13 September 1984, St. Petersburg (FL) Times, pg. 1D, col. 3:
A survival course in hash-house Greek
By DAN CARLINSKY
 
Google Books
The City in Slang: New York Life and Popular Speech
By Irving Lewis Allen
New York, NY: Oxford University Press
1993
Pg. 98:
by the 1930s this lingo was called hash-house Greek—in the sense of any unintelligible choctaw. These words and phrases were useful and fun for the customers, too, and the most common items leaked into general slang. COuntless word lists of lunch-counter lingo were published as light features in newspapers and magazines over the years and undoubtedly helped its spread. Some of the terms today are widely used, such as BLT ( a bacon, letuce, and tomato sandwich), sunny-side up (eggs fried on one side with (Pg. 99—ed.) the yolk unbroken), O.J. (a glass of orange juice), a stack (of pancakes), and a cuppa (a cup of coffee).
 
Google Books
Sundae Best:
A history of soda fountains
By Anne Cooper Funderburg
Bowling Green, OH: Bowling Green State University Popular Press
2002
Pg. 159:
HASH-HOUSE GREEK
Over the years, eateries spawned a language all their own, which came to be called “hash-house Greek.” Cooks and waiters, like workers in many fields, developed their own special jargon to facilitate their work. Many of the terms were a verbal shorthand used to communicate orders quickly, but hash-house Greek was more than that. It was a colorful argot used for the entertainment of customers and the amusement of the workers, to brighten up their tedious workday. In a few cases, it was also intended to spare the customer embarrassment—for example, when someone tried to leave without paying his check.