Used in almost every situation where one wants to express an emotion where they feel something was obnoxious, illogical, non-sensical, ridiculous, or insulting towards them
(Note: You MUST stress the "O" in "OKay")

best response to anything bad happening

words commonly used when you say "hi" or "hello" to someone and they either didn't see or hear you or just ignored you. This is used when around large groups of people and you feel awkward that the person either ignored you or didnt see you.