drop a dime

The phrase "drop a dime" typically means to inform or report to someone in authority about a crime, suspicious activity, or wrongdoing. It originates from the time when payphones required ten cents (a dime) to make a call. People would "drop a dime" into a payphone to anonymously report information to law enforcement or other relevant parties. The phrase has now evolved to include any act of providing information or tipping off about a situation.