ball bag vs knacker

ball bag

noun
  • The scrotum. 

knacker

noun
  • A testicle. 

  • One who makes knickknacks, toys, etc. 

  • A member of the Travelling Community; a Gypsy. 

  • One who slaughters and (especially) renders worn-out livestock (especially horses) and sells their flesh, bones and hides. 

  • A person of lower social class; a chav, skanger or scobe. 

  • One who dismantles old ships, houses, etc. and sells their components. 

  • A harness maker. 

  • One of two or more pieces of bone or wood held loosely between the fingers, and struck together by moving the hand; a clapper. 

  • An old, worn-out horse. 

verb
  • To reprimand. 

  • To tire out, exhaust. 

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