red box

/R EH1 D B AA0 K S/
noun
  1. 1

    A phreaking device that generates tones to simulate the insertion of coins into a payphone, thus enabling the user to make illegitimate free calls.

  2. 2

    A secure briefcase-like box used by ministers in the British government to carry their documents.

  3. 3

    A safe located at a nuclear installation containing launch codes.

  4. 4

    A "tornado watch" notification, indicating that conditions might lead to a tornado though none has yet been sighted.

Source: https://en.wiktionary.org/wiki/red%20box