Thing vs pink slip

Thing

noun
  • Nickname or appellative for numerous "things", including fictional characters. 

  • A public assembly or judicial council in a Germanic country. 

  • Nickname for the Volkswagen 181. 

pink slip

noun
  • Notice of termination of employment. 

  • An automobile roadworthiness inspection certificate. 

  • The title document for an automobile. 

verb
  • To terminate the employment of. 

How often have the words Thing and pink slip occurred in a corpus of books? (source: Google Ngram Viewer )