dime-dropper AmE slang

I presume some people do, because there it is in last week's Time about a dime-dropper who got his clock cleaned by history.

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.

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.