It's certainly irresponsible to talk of it even if you're going to do it. Got to be careful and not crash the currency.
It's fairly amazing the Euro zone countries have shared a currency for so long without much more centralized control. I can't think of any other examples. There was the Central French African franc zone, but one power, France, controlled the strings. France used the CFAF to finance its deficit spending, but in return the African countries got a stable currency.
In the Eurozone, France uses its power to avoid penalties for exceeding deficit standards, which insofar other countries are so penalized France benefits by relatively larger domestic deficit spending, the ill effects not limited domestically but shared with other Eurozone nations.
Indeed, that's why the UK distrusts the EU because of France.