whisper number
n.— «Rumor-mongering, of course, has long been the stock in trade of some on Wall Street. Billions of dollars a day are bet on “whisper numbers” and overheard lunchtime chatter. Information is the coin of the realm. Some of it is legal. Some of it is not. Just ask Ivan Boesky.» —“Psst! Hear the Rumor of the Day?” by Andrew Ross Sorkin New York Times July 8, 2008. (source: Double-Tongued Dictionary)