dickhead vs knob-end

dickhead

noun
  • The glans penis. 

  • A jerk; a mean or rude person. 

  • A stupid or useless person. 

knob-end

noun
  • The glans penis 

  • Used other than figuratively or idiomatically: see knob, end. The end of something that is shaped into a knob. 

  • A stupid or contemptible person 

How often have the words dickhead and knob-end occurred in a corpus of books? (source: Google Ngram Viewer )