(UK, dated) Used to add emphasis to, and to seek agreement with, a previous statement.

(idiomatic) Precisely what the situation really is or what the facts truly are; the true state of things.

Alternative form of what's what

(euphemistic, African-American Vernacular) What the hell.

For what purpose. / (colloquial) For what reason; why.

(idiomatic, colloquial, usually with "give someone") An unspecified punishment or rebuke

What is. / What has. / What does.

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

(idiomatic, dated) Something of the kind, whatever (used to terminate a vague list).

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