The honk comes from the Hanna-Barbera cartoon sound library, where bulb horns were a stock effect for clowns, bicycles and slapstick entrances in classic animated shorts. Catalogued as a medium clown bicycle bulb horn squeeze, it was designed to be instantly funny without any dialogue. Later, soundboard users and meme editors picked up the same short clip because its rubbery, old-fashioned tone reads immediately as a joke. It survives because it needs no context: one quick squeeze signals silliness in less than a second.