(idiomatic, rhetorical question) Why are you complaining? What are you complaining about?

An informal greeting.

Used other than figuratively or idiomatically: see what, is, the, difference. / (idiomatic) The difference does not matter; so what?

(informal, rhetorical question, sometimes sarcastic) Rhetorically implying that what is spoken of is undoubtedly good.

Used to argue that something's name is arbitrary and does not give any information as to its qualities; the names of things do not affect what they really are.

(slang) What's going on? How are you doing? What's new with you?

(slang) What happened, is happening, or is going to happen? Why did something happen or is someone acting a certain way?

(slang) What's going on? What are you trying to pull? (said when one is suspicious of someone else)

(informal, humorous) How much does it cost?

(UK, informal) How much do you want to bet that …?