A real common
italian interjection, it literally means "God is a pig".
Mostly used in northern
Italy, but known and understood everywhere.
Due to its blasphemic nature, it may be disturbing for some
people hearing this, especially Christians. It's not advisable to insert a "porco dio" into a sentence if you don't know well the person who you're talking at.
It has various forms and variations,
like "orcoddio", "dio porco", "dio maiale" ecc... and every form is also customizable on your personal preference ("Porco dio bastardo cane
e la madonna puttana" is a way stronger and powerful exclamation)
It's an all-round imprecation, usable in almost every sentence you can think about:
1) Expressing annoyance - "Ma porco dio la smetti di scassare i coglioni?" ("Porco dio can you please stop trying to smash my testicles?")
2) Expressing surprise - "Luca porco dio guarda quella che tette!" ("Porco dio Luca did you see that booby
girl?")
3) Expressing
pain - "Aaaaah! Porco dio che male!" - ("Aaaaah! Porco dio it hurts!")
4) Nothing at all, put into a normal sentence just to let the
people around you know who's the real alpha male - "Ciao Enrico come stai, porco dio?" - ("What's up Enrico, porco dio?")