As says our colleague and Chilean educator Lidia Ines is a Spanish form of the OK ( 41 okey; English whose origin is controversial. I'll stick with the military, that would mean zero dead ( 0 killed ) with that ended the parts of war of the US Army. In the Castilian use means " agree, is worth, I think it is good, Yes, in that we were " I usually tell people at the end of the telephone conversation or not. My daughters also used it in the wassap to express compliance with something, although usually it write with 40 k; okis ).