what どないやねん means?
 

ごはんはすごいよないと困るよ　むしろごはんがおかず だよ
関西人ならやっぱりお好み焼き＆ごはん
でも私関西人じゃないんです（どないやねん！）

どないやねん！

You picked a good phrase. I don't think there is a direct translation in English, but I hear it used as a rhetorical "What is this BS?" or "What am I going to do?" kind of phrase.

It's Kansai-ben, and it's more or less equivalent to 「どういうことですか」(Why is that?),「どうして」(Why?)or 「なんで」(Why?).

In the context you provided, I think it roughly means "What were you saying?!"

thanks a lot

You're welcome.