drop a dime
告密，向警方透露关键信息
口语·犯罪或执法语境，表示告密
英文释义
to make a telephone call, typically to provide information or report someone to the authorities, often anonymously
例句
He dropped a dime on his neighbor for running an illegal business.
典故来源
源自美国公共电话投币时代，打一次电话需投一枚10美分硬币，常指匿名向警方告密。