grenade vs trip switch

grenade

noun
  • A small explosive device, designed to be thrown by hand or launched using a rifle, grenade launcher, or rocket. 

  • An unattractive girl. 

  • A charge similar to a fireball, and made of a disc-shaped bomb shell, but with only one set of flames at the top. 

verb
  • To use grenade(s) upon. 

trip switch

noun
  • A device that deactivates an electrical circuit under certain conditions, often for safety reasons 

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