I don't know nothing

前一段時間，去華盛頓玩，我向一個由日本到美國的中國博士打聽一件事，他回答說
「I don't know nothing」。我感覺這話不符合語法習慣，「you don't know nothing」
means "you know everything"。顯然這不是他要表達的。正確的說法應該是"I know
nothing"或"I don't know anything"或更簡單一點"I don't know"。這件事過去了，
我也就不想它了。然而，最近我發現我們實驗室的一個美國黑人也說「I don't know
nothing」。是不是我錯了？還是因為走的人多了，就成了路。

You are right and wrong on this.

You are right: "I KNOW NOTHING" is proper English. No double negation in general. You won't be able to hear someone speaking like that in Britain.

And you are wrong: "I DON'T KNOW NOTHING" or "I DON"T TELL YOU NOTHING" is popular English in the American mid west. Just watch those westerns, you will notice many popular ways of speaking English like that. This is due to the earlier under-educated immigrants from Ireland, Walse or England. But be careful when you talk like that with non-Americans. It's sure as hell it won't be appreciated.

對呀。。很多人都把這個搞錯了呀。。。其實應該是「i know nothing"

i want to know more about the American's native culture and you can bring in me into the english heaven!thanks ,