1
general::
Phrase(s): duck soup
Fig. very easy; an easy thing to do. • For Maria, knitting a sweater is duck soup. • Jill: This jar is stuck. Could you open it for me? Jane: Sure. Duck soup.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
An easily accomplished task or assignment, a cinch to succeed, as in Fixing this car is going to be duck soup. This expression gained currency as the title of a hilarious popular movie by the Marx Brothers (1933). The original allusion has been lost. [Early 1900s]
American Heritage Idioms