(informal) To speculate about the consequences of something that could have happened.

Used to ask the listener what they want.

Used to introduce a suggestion or proposal for a future event. / Used to introduce a speculation about a future event.

(idiomatic) Or something else; allows for the existence of an unexpressed alternative to what was said.

(US) A shop selling miscellanea.

plural of what-not shop

Alternative form of know what is what

(idiomatic) To be experienced or well-informed. / (idiomatic) To be astute, perceptive enough to observe a situation that is not what it seems and recognize its true nature.

(defensively) Why are you asking? Why do you want to know?. / Mind your own business; it's none of your business.

(idiomatic, colloquial) What did you say?; Huh?; expresses incredulity.