DROP A DIME / DROP THE DIME (on someone): To inform on or betray. Originally underworld lingo meaning to give information to the police, RAT ON, SQUEAL ON, SNITCH. The expression, still in use, is of U.S. origin and dates from the 1960s, when a public pay telephone call cost 10 cents and a dime was inserted (dropped) into the slot. Such a call could be made to the police by an anonymous informer without the fear of being traced. <“There’s no cheating in this class because someone is bound to drop a dime and tell the teacher.”> And DIME DROPPER, of course, refers to a ‘tipster,’ a ‘rat,’ a ‘snitch,’ ‘a stool pigeon.’
On Language by William Safire, February 22, 1998:
DROP THAT DIME: ‘When you hook a wire to somebody,’ complained Paul Begala, an aide to President Clinton angry at the investigative techniques of the office of independent counsel, ‘ . . . and then you turn and drop the dime in a phone and call the press, that’s not the kind of investigation people need.’
Most people under 40 would find that reference to a coin baffling. One does not get a dial tone with anything less than a quarter; in Washington and environs, the price of a local call from a coin-operated phone has just gone up to 35 cents. Is the President’s defender unaware of the ravages of inflation over the past generation?
No: he was speaking metaphorically, and metaphors do not take seasonal or even generational adjustment. To drop a dime, in underworld lingo, has meant ‘to inform the police,’ with the squealing being done over the telephone, often anonymously by the informer, who is referred to by the squealed-upon as a rat, fink, snitch or tipster.
The recipient of the call refers to the fink as a whistle-blower. Different figures of speech for different folks: a bad guy doing good inserts a coin to make a surreptitious call, making himself a dime dropper, while a good guy blows a piercing whistle, making himself a much admired (though sometimes prosecuted) whistle blower.
Mr. Begala has extended the coin metaphor from an informant calling the police to a police source calling the press. In so doing, he takes the shadiness attached to the dime-dropper ratting on his underworld buddies and imputes it to the police source speaking to the press. In his extension, however, the spinmeister has not spoiled the trope by trying to update it saying something awkward as ‘the manipulative investigator dropped a dime plus a quarter to leak to the media.’ That would spoil the effect.
That’s how we intentionally preserve anachronisms. Feel free to have your dialing machine leave a message on my answering machine about all this; it’s your nickel.
(Oxford Dictionary of Idioms, Facts on File Encyclopedia of Word and Phrase Origins, American Heritage Dictionary of Slang, Cassell’s Dictionary of Slang, Brewer’s Dictionary of Modern Phrase & Fable, Chapman’s Dictionary of American Slang)<1972 “Louis Trueluck, 41, ended his testimony yesterday in Black Panther raid case by denying . . . he gave police the information that led to the Dec. 4, 1969 raid. ‘That’s a lie,’ said Trueluck when asked by Defense Atty. John Coglan, ‘Did you DROP THE DIME on the chairman’s crib?’ ‘DROP THE DIME’ is Black Panther slang for inform. ‘Crib’ was the Panther apartment. The chairman was Fred Hampton, 21, Illinois chairman of the Black Panther Party.”—‘Chicago Tribune,’ 26 August, page 19>
<1985 “Not surprisingly, crime is a topic rich in slang expressions. To inform on someone is ‘TO DROP THE DIME’ or ‘to eat the cheese’ (probably derived from the slang ‘to rat’ on someone).”—‘Western Folklore,’ Vol. 44, No.1, January, page 10>
<1990 “In fact, Uncle Dixon says, on second thought, he will turn John in. . . . Dixon says he’s thought it over, the best course for him is just to DROP THE DIME on John.”—‘The Burden of Proof’ by Scott Turow, page 512>
<1997 “. . .‘you DROP A DIME, which means you call in a 'shots fired' alarm to 911. Sometimes you even fire your own gun. Then you wait for the shots-fired call to come over the radio, and you respond to your own call. It's all made up, but it makes the raid legal.’" [[article - How Cops Go Bad]]— ‘Time Magazine,' 15 December>
<2006 “Judas Iscariot, vilified in the Gospels as Jesus’ great betrayer, was not merely an Apostle–he was perhaps Christ’s closest confidant. Technically speaking, he did DROP A DIME on Jesus”—‘Time Magazine,’ 27 February>
Ken G – March 13, 2006