bag of nerves vs donkey

bag of nerves

noun

  • A very nervous person. 

donkey

noun

  • A stubborn person. 

  • A bad poker player. 

  • A fool. 

  • A small auxiliary engine. 

  • A domestic animal, Equus asinus asinus, similar to a horse. 

How often have the words bag of nerves and donkey occurred in a corpus of books? (source: Google Ngram Viewer )