mugger vs pipe snake

mugger

noun
  • A large crocodile, Crocodylus palustris, of southwest Asia, having a very broad wrinkled snout. 

  • A person who assaults and robs others, especially in a public place. 

  • A person who makes exaggerated faces, as a performance; a gurner. 

pipe snake

noun
  • Shieldtail snake, family Uropeltidae. 

  • Synonym of plumber's snake 

How often have the words mugger and pipe snake occurred in a corpus of books? (source: Google Ngram Viewer )