Unfortunately where I live, some people speak like that quite frequently. It drives me mad.
I do need to correct the translation of your second sentence. Literally, the sentence does mean that whoever is speaking has done something to the other person in question (because of the double negative, etc.), but practically speaking when you hear someone say this, they are defending themselves in that they haven't done anything to the person in question. They actually mean that they haven't done anything to that person, etc.
P1: "Man, I just got the cold shoulder from this girl at da club."
P2: "Why she trippin?"
P1: "I don't know, man. I didn't do nothin' to her!"
I don't suggest using those sentences in normal conversation, but it's good to understand what they mean if you hear them.