What sort of usage is this?

[Unregistered]

I am a learner of English language. I have heard such usage in some TV episodes:

"I says" (not "I say")
"He don't" (not he does not)

- Is there a rule for this kind of usage?
- Is there any study source on Internet for studying this unusual usage?

I apologize if this subject has already been covered somewhere in this blog. But I do not know how to search for this.

 

[Raymott]

I am a learner of English language. I have heard such usage in some TV episodes:

"I says" (not "I say")
"He don't" (not he does not)

- Is there a rule for this kind of usage?
- Is there any study source on Internet for studying this unusual usage?

I apologize if this subject has already been covered somewhere in this blog. But I do not know how to search for this.

Not everybody speaks correctly - even characters on TV.
If you're interested in variations of speech due to social class (sociolects) or geography (dialects) etc., you could start by searching under those words.