bush telegraph

noun2

1. •
   A system used by undeveloped societies in remote regions for communication over long distances, such as drum sounds, word-of-mouth relay, or smoke signals.
2. •
   A gossip network.

   • I suppose you've received information, by bush-telegraph, that that third assistant understrapper and ex-sailorman at Tulagi is going to deport me as an undesirable immigrant. — 1911