I heared that the work OK was short for the name of a street in Vietnam where the prostitutes hung out. The street name pronounciation was something like.."Hunkydory".....
when the soldiers were at ease with the war torn country and had time on their hands a great deal of this would be spent in the clubs and bars in Hunkydory road. How true this is i dont know but does sound original. Horky Dorky... Okay...OK. lol.