なんでやねんwhat the hell, what the fuck, what are you going on about, you've got to be kidding

娘(むすめ)：「高校(こうこう)やめた。」母(はは)：「なんでやねん！」

Daughter: 'I quit high school.' Mother: 'Are you kidding me!?'

突然(とつぜん)話(はな)しかけられる、「なんでやねん！びっくりしたやろ！」

Some suddenly started talking to me. 'What the hell! You scared me!'

漫才(まんざい)を見(み)ていると「なんでやねん！」というセリフをよく聞(き)きます。

When watching comedy skits, you often hear the line 'What the hell!'

日本(にほん)のお笑(わら)いでは、ボケに「なんでやねん！」とツッコミを入(い)れる事(こと)になっています。

In Japanese comedy, the straight man is expected to respond to the funny man with a 'What the hell!?'

深夜(しんや)、夫(おっと)：「これからテニスしようや！」妻(つま)：「なんでやねん！もう夜(よる)も遅(おそ)いで！」

Husband, late at night: 'Let's play tennis now!' Wife: 'You've got to be kidding me! It's already late at night!'