cherry pie vs duck soup

cherry pie

noun
  • A pie baked with a cherry filling. 

  • Heliotropium arborescens. 

  • Any of various willowherbs 

duck soup

noun
  • Something which is easy; a piece of cake. 

  • Used other than figuratively or idiomatically: see duck, soup. 

How often have the words cherry pie and duck soup occurred in a corpus of books? (source: Google Ngram Viewer )