furphy

Etymology
From. The firm of (still in business today ) manufactured and supplied water carts to the Australian Imperial Force in Egypt during World War I. Soldiers stood around these and talked, exchanging rumours and news. The manufacturer's name, which was emblazoned on the carts, was soon adopted for unreliable information or speculation.

Noun

 * 1)  A rumour, or an erroneous or improbable story.