Aguri? If you mean auguri, yes, they do say that. But like I've said before, you don't know what auguri means. It's not just for Christmas. And given the fact that you said Merry Christmas in all other languages (although you fucked up in both French and German as well), I am pretty damn sure that you should have said Buon Natale.
And what's up with Naples? You're probably thinking it's cool to say they speak Italian like that down there? Well I've got news for you, fellow, they'll probably say something in dialect and it won't be tanti auguri. It's also the first time I have ever seen something act as if they speak the "real" Italian in Naples. Really shows how ignorant you must be about the subject. And last but not least, they say tanti auguri in every other Italian city as well.
Ma va bene, che ne so io?
Oh, and not a single German ever says frohliche.
Moron.