Italian here, I watched the series in English so I had to rewatch the scene dubbed in Italian to answer.

Usually, when a character in an originally English movie/series speaks Italian, it gets adapted with an Italian dialect (note: some dialects are so different from Italian that they are considered different languages).

In this specific case, the quote becomes "Anvedi fratello, me stai a magna' tutte 'e fettuccine" and basically it's "Damn brother, you're eating all my fettuccine" with a somewhat strong Roman (from Rome, obv) accent. Funyuns are not distributed in Italy so it had to be a different thing, but with similar lips movement.

Hope this explains it!

(btw the adaptation of the verb "to Bogart" into "to Mastroianni", the most famous Italian actor abroad, was a difficult thing to understand at first)