fire in one's belly vs spunk

fire in one's belly

spunk

noun

  • An attractive person (normally male). 

  • Touchwood; tinder. 

  • Courage; spirit; mettle; determination. 

  • Semen. 

verb

  • To ejaculate. 

  • To waste (money etc.). 

How often have the words fire in one's belly and spunk occurred in a corpus of books? (source: Google Ngram Viewer )