Instant Coolness in Japanese （なんで やねん）

He Says:
nande yanen!　（なんで　やねん）=Why!
Originally, naze?= why?.
nande yanen is Osakan one, so it's a dirtier or more curt way. But many japanese comedians are from Osaka, and they love to use nande yanen,so it sounds fun for many people.
For example,when you buy a few foods in a grocery store, if the casher says total is "$1 million", you can say nande yanen!.
That sounds funny, because jp comedians use the word for punchline of a joke.
Then many people laugh.
You can definitely get laugh in japan when you say this word, but softly please.If you say it loudly,they feel you are just so angry.
Variations:
dirtiest-nande jya!
dirtier-nande yanen!
normal-nande?
polite-naze? or dousite?

She Says:
I think that this is an example of Japanese humor not translating into English well. For an American, the funny part about the example He used would be that the total was "$1 million" for just a few things. However, in Japan, the funny part is that the comedian responds to this by saying "Why??" I don't why. Or should I say "Nande yanen?"
The one thing I do know is that using this word as a foreigner will make you seem "in the know" and will make Japanese people laugh.
This word is usually said in a moment of incredulousness and in a somewhat whiney voice.

The next word is...バーコード。