brass ovaries vs prowess

brass ovaries

noun
  • courage, guts 

prowess

noun
  • Distinguished bravery or courage, especially in battle; heroism. 

  • An act of distinguished bravery or courage; a heroic deed. 

  • Skillfulness and manual ability; adroitness or dexterity. 

  • An act of adroitness or dexterity. 

How often have the words brass ovaries and prowess occurred in a corpus of books? (source: Google Ngram Viewer )