grass on (one)

grass on (one)

slang To inform against a criminal or wrongdoer to a figure of authority. Primarily heard in UK. I'm afraid the Mafia will make a hit on me since I grassed on them to the police about their money-laundering operation. Why would you grass on me to the teacher like that?
See also: grass, on
Farlex Dictionary of Idioms.
See also:
  • grasse
  • snitch on
  • snitch on (one)
  • grass up
  • squeal on
  • squeal on (one)
  • make someone
  • gen up on (something)
  • inform against (one)
  • tattle