I don't get this joke:
It smells like up dog in here,
What's up dog?
Nuuthin dog, what's up with you?
I understand that the person asking "What's up dog" is tricked into asking a question they didn't intend to ask. I also understand the meaning of the "What's up?" question.
I don't understand why this exact question has been chosen. If anything, it sounds demeaning to the person who's making the joke and is referred to as dog by the receiver of the joke.
If I were to make a similar joke, I'd replace dog with something like master, so that it'd sound like the receiver of the joke respects the person making the joke more than it might be in reality.
Does the word dog in this context have some alternative meaning, perhaps?
Or is this joke funny simply because the receiver of the joke asks a funny question, no matter what the question is?