impregnate vs with a bun in the oven

impregnate

verb
  • To saturate, or infuse. 

  • To fill pores or spaces with a substance. 

  • To fertilize. 

  • To cause to become pregnant. 

with a bun in the oven

How often have the words impregnate and with a bun in the oven occurred in a corpus of books? (source: Google Ngram Viewer )