Foghorns have long been used on ships and in harbours to warn other vessels in low visibility, and that real-world purpose gives the sound its instantly recognisable sense of scale and danger. Online, a deep foghorn blast has become a go-to stock effect for editors who want instant atmosphere without dialogue or music. It appears in gaming videos, horror edits and meme compilations, where a single long blast can signal arrival, doom or a dramatic twist. Its simplicity is part of its staying power, because listeners understand the warning immediately, even out of context.