Alternative form of なんまんだぶ (nan man da bu)

surprise; astonishment; shock

what

何: how many; many

(dialectal, chiefly Kansai) Synonym of なの (na no)

男: man; son / 難: difficulty

軟: soft

難問: difficult problem / 南門: south gate

これは何ですか: what is this?

come again? what did you say again? (asking the listener to repeat what was said) / what!? (expressing disbelief and shock)