beat a retreat vs crawfish

beat a retreat

verb
  • To leave hastily in the face of opposition. 

crawfish

verb
  • To backpedal, desert or withdraw (also used with out). 

noun
  • Various marine crustaceans, rock lobster; especially Jasus lalandii, the Cape crawfish. 

  • Various freshwater crustaceans, crayfish. 

  • A slur against Anglo-Canadians used in some corners of Quebec (including the Gaspé). 

How often have the words beat a retreat and crawfish occurred in a corpus of books? (source: Google Ngram Viewer )