Have you ever ever been grassed up or grassed on?

Within the UK, to grass somebody up or to grass on somebody means to betray them to the police or different authorities, and a grass is an informer who betrays a bunch (of criminals or different ne’er-do-wells) to the police. It’s additionally used to imply telling on somebody to a determine of authority, resembling a boss, instructor or father or mother [source].

Grass in these senses might be a shortening of grasshopper, which is rhyming slang for copper (police officer), as in somebody who will inform on you to the police, and/or rhyming slang for shopper, i.e. one who ‘outlets’ you to the authorities [source].

A grasshopper can be:

• a largely herbivorous insect of the order Orthoptera.
• A cocktail made with crème de menthe and optionally with crème de cacao.
• A younger pupil in preliminary phases of coaching who has been chosen on account of their apparent expertise. [source]

Different phrases for an informant apparently embody: bigmouth, canary, fink, gossip, leak, mole, nark, quisling, sneak, snitch, snout, squealer, stooge, stool pigeon, stoolie, tattler, tattletale, telltale tit, telltale, tout and whistleblower [source].

Do you utilize any of those, or are there others you already know/use?

Are there fascinating phrases for informants in different languages?