To drop a dime (on someone) means to inform on them or betray them, usually to the police.
The expression “drop a dime” usually refers to informing the police or other investigators about someone’s illegal activity, but it is sometimes used for more general, and less serious circumstances, whenever someone informs on another person’s infractions.
“At the Drop of a Dime” vs. “At the Drop of a Hat” (The Mix-Up)
A frequent error among speakers is combining two separate expressions into the hybrid phrase “at the drop of a dime.” This is a malapropism (or idiom blend) caused by confusing three distinct idioms involving the word drop or dime:
- At the Drop of a Hat (The Intended Saying): Doing something immediately, spontaneously, or without any hesitation or planning: “He’s ready to pack his bags and travel at the drop of a hat.”
- Drop a Dime: Underworld slang meaning to inform or snitch on someone to law enforcement: “Someone dropped a dime on the warehouse operation.”
- Stop on a Dime: An automotive and mechanical idiom referring to the ability to stop or turn within an extremely short distance with great precision.
Saying that someone will do something “at the drop of a dime” accidentally merges immediate action with police informing. Unless the context literally involves snitching at a moment’s notice, the correct phrase to express instant action is always at the drop of a hat.
Origin of “Drop a Dime”
The idiom originated in American underworld and police slang during the mid-20th century, emerging into common print during the 1960s. It refers directly to the literal mechanism and cost of public pay phones.
For decades across mid-century America, placing a local call from a public pay telephone cost exactly ten cents: a dime. An informant, criminal collaborator, or tipster seeking to report illicit activity anonymously would slip into a street phone booth, drop a ten-cent coin into the mechanical coin slot, and dial the local police precinct or FBI field office.
The physical sound and action of the coin falling through the internal trip mechanism into the locked deposit box became synonymous with betraying a partner in crime.
Evolution into Modern Slang (“Dime Out”)
While modern pay phones are virtually obsolete and cell phones have replaced coin-operated calls, the phrase remains a permanent fixture of crime fiction, film, and everyday speech. It also evolved into the transitive phrasal verb to dime (someone) out, carrying the exact same meaning: “He got arrested and immediately dimed out the entire crew.”
Sentence Examples
“Mary is such a teacher’s pet. She dropped a dime on me for sneaking out while the teacher was away.”
“The only way he can avoid a prison sentence is to drop the dime on his former employer.”
“I never dropped a dime on Ricardo. We’ve been best friends since we were kids.”
Similar and Related Idioms
- At the Drop of a Hat: Instantly, promptly, or without any hesitation or prior planning.
- Blow the Whistle: To report illegal, unethical, or illicit activity within an organization to authorities or the public.
- Spill the Beans: To prematurely reveal a secret or disclose confidential information.
- Sing Like a Canary: Underworld slang meaning to confess everything and inform extensively to the police.
- Rat Out: To betray or inform on an associate or accomplice to an authority figure.
- Turn State’s Evidence: A legal term for an accomplice who agrees to testify against former co-defendants in exchange for immunity or a lighter sentence.