What does "what for" mean?

An unspecified punishment or rebuke.

What is a synonym for "what for"?

Common synonyms include: ass-reaming, bawling-out, castigation, chastening, chastisement, chewing.

adv, noun, slang

adv, noun, slang ·Moderate ·High school level

Noun

1
An unspecified punishment or rebuke. colloquial, idiomatic, usually
"When your dad gets home, he'll give you (a) what for."
2
a strong reprimand wordnet

Adverb

1
For what purpose. not-comparable
"What is this tool for?"
2
For what reason; why. colloquial, not-comparable
"He wants four copies of it? What for?"

"He wants four copies of it? What for?"