nobody vs weak sister

nobody

noun
  • Someone who is not important or well-known. 

pron
  • Not any person; the logical negation of somebody. 

weak sister

noun
  • A person who is cowardly or indecisive. 

  • A person or thing which is the least robust or least dependable member of a group. 

How often have the words nobody and weak sister occurred in a corpus of books? (source: Google Ngram Viewer )