dak vs mailshot

dak

noun
  • A post system by means of transport relays of horses stationed at intervals along a route or network, carrying mail and passengers. 

  • A dak bungalow. 

verb
  • To suddenly pull down someone's pants as a prank; to pants. 

mailshot

noun
  • Bulk advertising sent through the post/mail. 

verb
  • To send bulk advertising to (somebody) in the post. 

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