なんでやねん nande yanen

Pull it apart and it is pure Kansai grammar: なんで, why, plus や, the local copula where Tokyo says だ, plus ねん, a sentence-ending particle with no standard equivalent at all. That is why the phrase feels so regional even to Japanese ears — you cannot render it in standard Japanese without losing the shape.

It lives in manzai, where the boke says something absurd and the tsukkomi fires this back, often with a light slap to the shoulder. Decades of televised comedy sent it nationwide, so everyone can produce the words. The pitch accent is another matter: say it outside Kansai and someone from Osaka will hear the seam immediately.