also: なにをゆうてんねん
Kansai-ben phrase expressing disbelief, frustration, or strong disagreement with what someone just said. Roughly equivalent to standard Japanese 何を言ってるんだよ.
"I'm going on a diet starting tomorrow" — what the hell are you saying? You said the same thing yesterday, didn't you?
What the hell are you talking about? There's no way that's true.
Standard Kansai-ben spelling with 言うてんねん.
Alternate spelling reflecting the colloquial pronunciation ゆう for 言う.
Kansai-ben contraction of 何を言っているのだ (nani o itte iru no da), with 言っている → 言うてる (yūteru) and のだ → ねん (nen).