BOB vs jill

BOB

noun
  • Vibrator (device designed to stimulate a woman's genitals). 

adj
  • Back-of-the-book; denoting those stamps in a catalogue that are not used for the payment of regular postage fees, and are displayed separately in the catalogue after that listing; the division between these two groups varies with the publisher. 

jill

noun
  • A pelvic protector, a woman’s equivalent of a man’s jock. 

  • Coordinate term: (sex) hob 

  • A female ferret. 

verb
  • To masturbate. 

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