blow the whistle on

blow the whistle on idiom
  1. Expose corruption or other wrongdoing, as in The President's speech blew the whistle on the opposition's leaking information. [Colloquial; 1930s]
  2. Put a stop to, as in The registry decided to blow the whistle on new vanity plates. The term originally alluded to ending an activity (such as factory work) with the blast of a whistle. [Late 1800s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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