The origins of the phrase "Drop a Dime" are, sadly, a thing of the past. For several decades spanning the middle of the 20th century, the initial charge for a call from a pay phone was 10 cents. The phrase became popular when anonymous informants would use pay phones to report unlawful behavior to law enforcement, otherwise known as "snitching". While calls from land lines could be traced, calls originating from pay phones could not. These days, the phrase refers any act of snitching, regardless of the means. I wonder how many dimes were dropped on the device that this prehistoric housing once contained.
And now I shall use the phrase in a sentence to demonstrate its use: "I'm pretty sure that Phil & Verla from Oz has been muggling my ammo cans. I'm about to drop a dime to Flatland Reviewer and burn his @$$ ." 
This should be a quick park and grab. Happy caching and stay safe.