Americans traditional eat turkey on Thanksgiving. A traditional Irish-American dish is corned beef and cabbage, and it’s often nicknamed “Irish turkey.” “Irish turkey with the shamrock!” stood for “corned beef and cabbage” in the Washington Standard (Olympia, WA) on April 27, 1894. The “Irish turkey” slang is still used, although much less frequently.
 
“Wreath” was slang for cabbage, so the order was sometimes “Irish turkey with a wreath.” However, the shortened “Irish turkey” usually meant the full dish of corned beef and cabbage.
 
Corned beef and cabbage (“Irish turkey”) has been frequently served in Irish-American households and restaurants on Thursdays and on St. Patrick’s Day (March 17th).
   
The dish of corned beef and cabbage has also been called “Jiggs dinner” and “Red Mike and Violets.”
     
     
Diner Lingo
Q: What does “Irish turkey” mean?
A: If you hear a waitress say “Irish turkey” at a diner or restaurant, it’s just another way to say “Corned beef and cabbage.” Also called “Irish turkey with a wreath.”
 
27 April 1894, Washington Standard (Olympia, WA), pg. 1, col. 5:
HASH-HOUSE PHRASES.
Olympia Waiters May Get a Few Pointers From the “Profesh.”
A Denver reporter undertook to go the rounds of some of the restaurants of that city, ...
(...)
A hungry railroad hand next sat down and ordered the following: “A bowl of soup, fricasseed chicken, corned beef and cabbage, two boiled eggs and fried sausage.” This is how the varlet gave the order in: “Bowl up! Chick one. Irish turkey with the shamrock! Boil two and a cable link!”
 
24 December 1894, Los Angeles (CA) Times, “Christmas Markets,” pg. 5, col. 7:
There are things there, fish, flesh and fowl, that would make a blind man see and cause the hungriest of stomachs to turn up the nose of its mucous membrane at the finest “Irish turkey”—otherwise known as corned beef and cabbage—that ever was boiled.
 
Chronicling America
18 January 1900, The National Tribune (Washington, DC), “California Pioneer Railroading” by Capt. Free S. Bowley, pg. 1, col. 5:
Among the items on the menu were “Irish turkey,” “Arizona chicken,” “jack rabbit fricassee—you shoot the rabbit,” “good bread and butter,” “strawberries.” We found the turkey to be corned beef, the chicken was boiled bacon, the strawberries big red beans, the “frijoles” of Mexico.
     
17 March 1904, The Oregon Daily Journal (Portland, OR), “Restaurant Talk Wins a Husband,” pg. 8, col. 5:
“I learned that pork and beans is called ‘Spokane,’ corned beef and cabbage ‘Irish turkey,’ and milk toast a ‘graveyard stew.’”
 
Google Books
October 1907, The Bookman, “Who Writes the Jokes?” by Arthur Sullivant Hoffman, pg. 174:
“I have a great weakness for a joke of mine which I have been unable to sell,” says Mr. Miller:
 
“If corned beef is Irish turkey, what is macaroni?
“Guiney-hen.”
 
1 February 1909, The Daily Missoulian (Missoula, MT), “Rosie Tells of Freak Orders,” pg. 4, col. 3:
“Irish turkey” means corned beef and cabbage.
     
24 June 1916, Brooklyn (NY) Daily Eagle, “Brooklyn Boys Working Hard in Soldier Camp,” pg. 3, col. 3:
Irish Tackle Commissary Summers.
No Corned Beef and Cabbage?
Offsprings of natives in the Emerald Isle were somewhat disappointed at not getting in a feed of corned beef and cabbage or “Red Mike” and “Irish Turkey,” as they referred to the popular dish before leaving for Peekskill.
 
29 May 1925, Trenton (NJ) Evening Times, pg. 5, col. 2:
CORNED BEEF AND CABBAGE IS FAVORITE DISH
NEW YORK, May 29.—Corned beef and cabbage—“Irish turkey”—is to try for the favorite dish of New York, judging from the first 2,000 ballots handed today to Calvin S. Klein, Secretary of the United Restaurant Owners’ Association.
(...)
In 1,200 of the first 2,000 ballots turned in, corned beef and cabbage was first choice.
 
Google Books
Dialect Notes, Volume 5
American Dialect Society
Tuscaloosa, AL: University of Alabama Press
1927
Pg. 451:
Irish turkey, n. Corned beef and cabbage.
   
14 January 1939, The Courier-Journal (Louisville, KY), “Striving for Status In Hash House Talk” by Lawrence Boeck, sec. 3, pg. 13, col. 2:
Irish turkey—Corned beef and cabbage.
 
Google Books
Criminal Slang:
The Vernacular of the Underworld Lingo
By Vincent Joseph Monteleone
Boston, MA: The Christopher Publishing House
1949
Pg. 129:
IRISH TURKEY (N) Corned beef.
   
7 May 1951, San Francisco (CA) Chronicle, “Back-Counter Slang Is Dying Out” by Dick Hemp, Gourmet Guide sec., pg. 14, col. 3:
Irish turkey
Corned beef and cabbage
   
15 March 1956, Indianapolis (IN)

, “Food” by Ann Harrington, pg. 12, col. 4:
It is a great day for the Irish when the main dish of the meal is brisket corned beef—which they sometimes call “Irish turkey.” By any name, tender, full-flavored corned beef is sure to make a delectable meal.
 
2 April 1967, Washington (DC) Post, “Letters to the Editor,” pg. C6, col. 4:
Alas and alack for all the hymns to “red mike and violets” and “Irish turkey,” corned beef and cabbage is not now and never was an Irish dish. Its origins are as American as apple pie and as Yankee as the clambake. It is, in short, the New England boiled dinner, which the Irish adopted because it clung warmly to their innards more comfortably and healthfully than potatoes alone, especially the blighted spuds which killed so many and drove millions to flee for life, but not for gourmet cookery.
(...)
WALTER TROHAN,
Correspondent, Washington Bureau, Chicago Tribune Press Service,
Washington.
 
11 October 1972, Daily News (New York, NY), “On the Town” by Charles McHarry, pg. 79, col. 1:
Irish Turkey
A few columns back we asked how come restaurants often feature corned beef and cabbage on Thursdays. Here with a handful of answers: ...
 
28 January 1987, Marshall (TX) News Messenger, “New book spotlights short-order cook terms” by Rhonda Hoeckley (Harte-Hanks News Service, pg. 5B, col. 2:
(The Dictionary of American Food by John Mariani.—ed.)
Irish turkey—corned beef and cabbage.
(...)
Wreath—cabbage.
 
Twitter
DARE
@darewords
Happy St. Pat’s weekend, folks. Have yourselves some Irish turkey — Irish turkey: corned beef, often with cabbage.
3:30 PM - 15 Mar 2013
 
Twitter
Bluebonnet Diner
@bluebonnetdiner
Diner logo time: Irish Turkey = Corned Beef and Cabbage
Joe O’Malley = Irish Coffee
💚Slainte & Happy St. Patrick’s Day
7:59 AM - 17 Mar 2017