关于ain't

美语中很常用的一个词,有高手能给我讲讲它的具体用法吗?
最好来点例句,谢谢
you ain't got no legs.如这个,ain't是否定的,最后怎么又来个no呢?
来自电影《阿甘正传》里的台词,是说你（丹中尉）没有腿。

ain't: [ eint ]

(=are not,am not)
“Ain’t” has a long and vital history as a substitute for “isn’t,” “aren’t” and so on. It was originally formed from a contraction of “am not” and is still commonly used in that sense. Even though it has been universally condemned as the classic “mistake” in English, everyone uses it occasionally as part of a joking phrase or to convey a down-to-earth quality. But if you always use it instead of the more “proper” contractions you’re sure to be branded as uneducated.

例：I ain't ready. （我还没准备好。） 例：I am very nice to you, aren't I? （我对你很不错，是不是？） 美国人用“ain't”很随便，应该是“are not，is not，have not，has not”的地方，他们也会“ain't”一下就带过去，宜注意。
Related Words and Usage
The related word hain’t is an archaic and non-standard contraction meaning has not or have not. It can be found in literature, particularly in Mark Twain’s stories such as The Adventures of Tom Sawyer. It is reminiscent of hae (have) in Lowland Scots.