latrine wireless(latrine wireless is the free exchange of information and gossip at the general toilet facilities: It came over the latrine wireless.Anglophile)
grapevine(hear something on the grapevine to hear about something because the information has been passed from one person to another in conversation: I heard about his resignation on the grapevine. LDCE Alexander Demidov)
jungle telegraph(An informal means of communication or information, especially gossip. Used most commonly in the phrase "hear (something) on the jungle telegraph." (Analogous to "hear (something) through the grapevine.") Primarily heard in UK: I heard on the jungle telegraph that Stacy and Mark are getting a divorce! • A: "How do you know the company is going bust?" B: "I heard it on the jungle telegraph."thefreedictionary.comAlexander Demidov)