bump off vs send to the glue factory

bump off

verb
  • To kill, especially to murder. 

  • To cut class; to play truant. 

send to the glue factory

verb
  • To kill, usually a horse. 

  • To retire or remove from prominence, usually due to obsolescence, old age or injury. 

How often have the words bump off and send to the glue factory occurred in a corpus of books? (source: Google Ngram Viewer )