The real meaning is Fuck you.
If you want to say "go take it in the ass" you can also say "Ma vattelo a pigliare in culo!

In Italian, it literally means "Go fuck an ass"

fuck you in Italian

It's an insult. Anyone who speaks Italian as a first language will tell you that it means "Fuck off". If Italian is not your native language, then you may interpret it as "Fuck an ass" or "Fuck your ass" or any combination of "ass" and "fuck". see previous entries

Literally means: Take it up the ass.

"go to do an ass" or "go to do in ass".....
But the real english translation is "Fuck you off", or may be "fuck you" i mean letterally. I say this from my 35 years old of REAL ITALIAN vaffanculo experience!.
Now other examples below..

On September 8 2007 five million Italians, leaded by the COMEDIAN Beppe Grillo went to over 200 squares in all the country to celebrate the Vaffanculo Day (also known as V-Day or Vaffa Day) to say vaffanculo to the corrupted and untouchable italian political class.
Another V-Day is ready for April 25 2008.