I'm a friends fan and I know that this word came out from Joey. But in fact in Italy we don't use it, we say vaffanculo... That it means "fuck you" ; "fuck off" Vafanapoli is like a more polite version, it means "go to Naples" va fa napoli"
We don’t use this word. I think in the show they wanted to say fuck off “vaffanculo” but couldn’t and used a different word, invented, similar in sound to give the idea. It’s also a little bit racist but yeah, who am I to judge 🤷🏼♀️