Everyday explained: Why Indian trucks have ‘Horn OK Please’ sign painted on the back

The 'Horn OK Please' sign on Indian trucks originated during World War II as a safety warning about kerosene fuel.

During the 1940s, diesel was shipped to Europe by the British, causing a diesel shortage in India, and kerosene was used as an alternative for trucks.

Kerosene-fueled trucks were highly unstable and could explode in accidents, so British authorities painted 'Horn Please On Kerosene' on truck backs to warn others.

Over time, the phrase was shortened to 'Horn OK Please,' with 'OK' standing for 'On Kerosene'.