In Chapter 32 of Treasure Island the pirates are absolutely terrified by the sound of a strange voice singing "Fifteen men on a dead man's chest/Yo-ho-ho and a bottle of rum." They think it's a ghost. Even the normally fearless Long John Silver's pretty spooked out by the weird-sounding voice. But he stands firm, nonetheless, and refuses to let his petrified crew turn back, not even when he hears the strange voice call out Flint's last words "Fetch aft the rum, Darby." Silver tells his men that the voice can't be a ghost's because it's echoing and ghosts' voices don't echo. They soon realize that the voice doesn't sound like Flint after all; it sounds more like Ben Gunn, and Silver's men aren't afraid of him.