rat on someone/something

SMART Vocabulary: related words and phrases

Revealing secrets & becoming known
anti-secrecy
backchannel
bare
bare your heart/soulidiom
blow someone's coveridiom
blow/take the lid off somethingidiom
declassify
hold
huddle
kiss
rat
rat on someone/something
reintroduce
revealingly
revelatory
state's evidence
surface
tip
transpire
unravel

fink on someone | American Dictionary

fink on someone

phrasal verb with finkverbus/fɪŋk/
slang
to tell secret and damaging information about someone:
Someone finked on him to the cops.