I wrote a bunch and then realized I misinterpreted the question. I'll leave the bunch because I think it is still useful.
I believe "You got me mad" uses "got" as a simple past tense of "get". So "now" doesn't make sense with it because "got" is in the past.
"You have got me mad now" is better because "have got" suggests that something in the past created a condition that exists now.
"You got me mad now", while incorrect, might be used in a meme or poster for the reason described below.
Most people would say, "You made me mad." Using "got" instead of "made" is sometimes used to suggest that the person speaking is uneducated or simple-minded. When trying to emphasize that you are stubborn or uncompromising, it can help to suggest that you don't think too much.
"Now" is used in the sentence to suggest that the the listener has done something, really bad. The listener may have done many bad things, but the speaker was willing to overlook them because the speaker is slow to anger. But now the listener has done something so bad that the speaker is finally angry.
"I didn't mind you flirting with my girlfriend. I ignored you borrowing my book and not returning it. I looked the other way when you put your feet on my table. But then you put pineapple on my pizza. You've got me mad now!"