Even trucks, who are not particularly equipped with side mirrors have this phrase painted on the back to urge drivers to use their horn as a signal to the truck driver when they are overtaking. 

One theory suggests that the “OK” should be read separately from “Horn Please” as it is intended to only appear to the eye when the driver behind the truck is at a safe distance. 

Apparently, when the driver moves too close to the truck, only “Horn Please” is visible. However, the validity of this theory is also questionable, given the fact that there is very little consistency in how the words are painted.

Well, there is another theory, that suggests that the “OK” actually means “On Kerosene” to urge drivers to keep their distance. Doesn’t make any sense?

Get this, During WWII there was a worldwide shortage of diesel and since kerosene was cheaper and easily available at that time, truck drivers preferred using kerosene. Who knew?

This theory definitely makes more sense than the previous one as Indian truck drivers still mix diesel with kerosene to save money on gas.  

That’s not all, though. There’s another theory that suggests, ‘OK’ was actually the name of a detergent that was launched, back then, by the Tata Group. 

And, they used these trucks as a medium of promotion so they usually painted ‘OK’ accompanied by a lotus flower, which is done even today. 

Just like us, people on Twitter were also fascinated by this intriguing fact, that most of us have been oblivious to.