die-in vs sit-in

die-in

noun
  • A form of protest where a group of people in a public area lie on the ground to simulate being dead. 

sit-in

noun
  • A peaceful form of protest in which people occupy an area and refuse to leave. 

adj
  • Designed to be sat in. 

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