Euphemistic form of what the fuck.

An intensive form of what.

(slang) what's happening?; what's up? (a greeting)

(informal) An informal greeting asking the other person what has recently happened in their life. A typical response might be "Not much; you?". The greeting is not always literal and may just be used to say hello.

(idiomatic) The latest developments in a particular situation or a person's life.

(followed by a phrase) Regardless, in spite of. / (not followed by a phrase) Regardless of any or most possible adverse circumstances.

Used to express regret or disappointment about an unfortunate event or piece of information.

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

(idiomatic, rhetorical question) Used to express surprise at an unlikely outcome.

An informal greeting.