punching bag vs tanker

punching bag

noun
  • A person serving as an object of abuse. 

  • A tough bag, usually cylindrical, filled with air, sand, or other material, often suspended so that it swings freely, which is punched or kicked when practising sports such as boxing or martial arts. 

tanker

noun
  • Member of a tank crew, or of an armoured unit. 

  • A tank ship, a vessel used to transport large quantities of liquid. 

  • A longboard. 

  • An aircraft built or modified to carry water and/or fire retardant for dropping on wildfires. 

  • A tank truck. 

  • A fuel tanker, petrol tanker, road tanker. 

  • An aircraft carrying a large supply of jet fuel or avgas for aerial refueling of other aircraft, plus equipment allowing the in-air transfer of fuel. 

  • A tank car. 

verb
  • To carry more fuel than necessary for a flight, in order to avoid having to refuel at a destination where fuel is more expensive or in short supply. 

  • To transport (oil, etc.) in a tanker. 

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