drop a dime on
US /drɑp ə daɪm ɑn/
UK /drɑp ə daɪm ɑn/
1.
to inform the police or other authorities about someone's illegal activities
:
•
He threatened to drop a dime on his accomplice if he didn't get a larger share.
•
Someone must have dropped a dime on them, that's how the police found out.