Used to make a suggestion. / Used to ask someone to consider something or someone that they have apparently not considered. / To repeat a question but referring to a different subject or object.

(idiomatic) what are the advantages of (something) to me, personally?

(idiomatic, Britain, colloquial) An intensified version of what or huh.

(colloquial, in rhetorical questions or salutations) What's wrong with; what's the problem or matter with. Said to express that the behaviour of someone, or operation of something, is out of the ordinary or problematic.

(idiomatic, colloquial, with up in the sense of "of concern") What’s the matter? What is the problem? What is wrong?

(interrogative, vulgar, slang) An intensive form of what.

(vulgar) Used to express astonishment, shock, incredulity, or disbelief (as a shortened form of expressions such as "What the fuck is going on?", "...are you doing?", "…is this?" "…is it" or "...is that?").

(idiomatic) What is wrong? What's the problem? / (dated) What's happening? What's the news?

(idiomatic) What is the purpose or advantage of

(idiomatic, informal) A greeting, similar to how are you?; what's happening?; what's up?; what's new?