grass up
Verb
Meaning
grass up (third-person singular simple present grasses up, present participle grassing up, simple past and past participle grassed up)
(UK, slang) To betray by informing on.
Verb
grass up (third-person singular simple present grasses up, present participle grassing up, simple past and past participle grassed up)
(UK, slang) To betray by informing on.