I didn't read the article (and from the comments here, it seems to be a waste of time), but there are 2 phrases in there: "Horn Please" and "OK"; it's not "Horn

I didn't read the article (and from the comments here, it seems to be a waste of time), but there are 2 phrases in there: "Horn Please" and "OK"; it's not "Horn OK Please", even though it's written that way. "Horn Please" is to tell the vehicle behind that they can sound the horn if they want to pass. "OK", I think, comes from "OK Tata" (as in "OK, bye bye").