what?!; what did you say?!
An exclamation of surprise or disbelief, often used when hearing unexpected news. Casual and conversational.
Huh, what?! Say that again.
He's quitting? What?!
why?; what for?
Used to ask the reason for something, often with a tone of surprise or demand. More emphatic than なぜ.
Why on earth did you do that?
Used in the pattern なんだって～ to mean 'anyone' or 'anything', similar to 何でも. Often followed by a verb like できる or いい.
See also: なんでも
なんだって今頃来たんだ？
What are you doing here at this hour?
He can do anything.
Anything is fine.
Contraction of 何と (なんと) and 言って (いって), literally 'what did you say?'. The adverbial uses developed from this interrogative origin.