Ok, someone pushed the red button. Everything blew up and the world has to start from scratch. You and a bunch of other people are lucky. You have the cockroach gene that allowed you to survive it. You get to make society from scratch, etiquette rules, political structure, economic model (capitalism or communism), religion, culture and custom, dress, the whole nine yards. What would your society look like?
This is a really fun question.
My imagination sucks, but let's see....
First of all, we'd all have to live underground like ants to escape the fallout.
Music would be the only form of communication. It would at least make life interesting. But opera would be banned.
The only "etiquette rule" would be to treat others with respect.
There would be no religion. Why would we need it anyway? Science and reason would reign. And science would not be used for destruction (like nuclear weapons) but for the betterment of humanity.
I support capitalism to an extent, but sorry people, socialism would have to be the economic model, when we're trying to preserve the human species.
We'd have to teach our decendants how to clean up the world from pollutants and radioactive material once humans can finally return above ground.
Everyone's vegetarian (assuming plants lived through the fallout).
Dress how you want, because at this point, who cares?
Violent people are discarded from society.
Women are treated with the utmost respect.
Women rule the world.
The best one of all: I'd be the leader of the world
But in all seriousness, let's just hope that button is never pushed.