Possible Duplicate:
The grammaticality of “that don’t impress me much”
“I don’t know nothing” vs “I don’t know anything”
I've noticed that sometimes people say "It don't mean nothing". But I would expect to hear "It doesn't mean anything" or at least "It doesn't mean nothing".
Could anyone clarify why is that? Or it's totally OK to say that?
Here is an example from the movie "Hamburger Hill", http://www.youtube.com/watch?v=ernKt7JpNfM