milkbag vs sternum

milkbag

noun
  • Breasts. 

  • A bag containing milk. 

sternum

noun
  • The breastbone, consisting of the manubrium, gladiolus, and xiphoid process. 

  • The sclerotized ventral plate of spiders, between the coxae, marking the floor of the cephalothorax. 

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