Duck Soup

Entry in progress—B.P.
 
Wikipedia: Duck Soup
Duck Soup is a 1933 Marx Brothers anarchic comedy film written by Bert Kalmar and Harry Ruby, with additional dialogue by Arthur Sheekman and Nat Perrin, and directed by Leo McCarey. First released theatrically by Paramount Pictures on November 17 1933, it starred what were then billed as the “Four Marx Brothers” (Groucho, Harpo, Chico, and Zeppo) and also featured Margaret Dumont, Raquel Torres, Louis Calhern and Edgar Kennedy. It was the last Marx Brothers film to feature Zeppo, and the last of five Marx Brothers movies released by Paramount.
   
Merriam-Webster Dictionary
Main Entry: duck soup
Function: noun
Date: 1912
: something easy to do
 
(Oxford English Dictionary)
duck soup
slang (orig. and chiefly U.S.), something requiring little effort; a person easy to overcome or cheat; a ‘cinch’
1912 A. H. LEWIS Apaches of N.Y. iv. 84 ‘Them Gophers are as tough a bunch as ever comes down the pike.’ ‘Tough nothin’!’ returned Slimmy: ‘they’ll be *duck soup to Ike.’
1929 D. HAMMETT Red Harvest xxvi. 257 it was a juicy row, while it lasted—no duck soup for the coppers at that.
1966 OGILVY & ANDERSON Excurs. Number Theory i. 4 The number 307 comes out, in binary notation, to be 100110011 which would not have the convenience of 307 at the grocery store, perhaps, but is duck soup for the Computer.
1966 B. E. WALLACE Murder in Touraine xvii. 52 Now all he had to do..was to..avoid a guard: it was going to be duck soup if you were the right kind of duck.
 
8 Nov. 1879, Mountain Democrat (Placerville, CA),  p. 4(?), col. 2:
HEROIC TREATMENT.—In surgery and medicine the above title is given to treatment which if it fails to cure is bound to kill the patient. In the latter case it is liable to also make duck soup of the practitioner’s reputation.

23 July 1897, Chicago (IL) Daily Tribune, pg. 10:
P. A. Brady, one of the more successful of retired bookmakers, and formerly an owner of race horses, said: “It has now come to an issue where every man must show his colors. I am out of the business and so this fight is duck soup for me.”
 
Google Books
August 1899, Recreation, pg. 139, col. 2:
My experience with Indians has satisfied me that a jail sentence, especially during the winter months, is just “duck soup” for the average blanketed hobo.
 
27 December 1903, Washington (DC) Post, “Baseball Gossip,” pg. E11:
“Duck soup is what you are for me,” sang Shreve as White missed the first ball by several inches.  “Oh how easy,” was the next rejoinder…
 
17 January 1910, Washington (DC) Post, baseball, pg. 8:
Washington was the real “duck soup” for the Sox, losing seven games to them,...