What is the meaning of ‘nandato’ usually heard all throughout the ‘Naruto Shipuudden’ series?

I keep on hearing the term “nandato” from the characters. I wonder what it means…

Usually Nandato means “what did u said”
Nandato litarally means “What did you say?”

it can also be translated in “What?” “What do you mean” “What the hell?” etc, depending on grammar & conversation and person habit/way of speaking.

Hiyori of Bleach always says that *ahahaha* (ahhhh… it makes me remember of what happened to her in the latest manga *schet* she’s my female favorite character)
naruto anime is the first then the second series is naruto sippudden~

just like vampire knight [1 series] vampire knight guity [2 series]
hmm i do not know, but while we are on the subject has Nandato replaced Dattebayo!?
Its’s a way of saying “What the hell?”