grass on

verb

grass on

verb

1

UK, Slang To betray by informing on.

What I was pissed off about, though, was him telling everyone that he'd only grassed on me because I'd grassed on him first, which was a total lie.2008, Danny King, School for Scumbags:

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.