It's not a witty joke. For it to be witty it would need to be relevant to the subject that was being discussed.
The point being discussed is that you are pumping up Brisbane (and you have done it a few times now) whilst hanging s*** on another place. Also, it has been a central theme/aspect of your argument and I find it hilarious.
Face it mate. Brisbane isn’t better or any more special than any other city in Australia. There are just as many bogans in Brisbane than anywhere else in Australia.