What's the beeped out Flag things?

It's not really Italian, just him saying "What's a come and a go?" with an accent.

Here's the wiki explanation for the flags:

Swearing

When Ferguson (and guests) swear on the show, rather than seeing pixelization over his lips and hearing a bleep, the viewers will sometimes see a flag appear over his lips and hear a corresponding phrase, such as:

Austria: "Strudel", "Edelweiss", "Wienerschnitzel"
Australia: "Dingo ate my baby", "Crikey!", and "Crikey dingo!"
France: "Ooh la la!", "Croissant", "Baguette", and "Sacrebleu"
Gay flag.svg (Rainbow Flag): "Uh oh!", "Hmmm!", and "Ohhh!"
Germany: "Ausfahrt!", "Auf Wiedersehen", and "Achtung!"
Italy: "Tutsi fruitsi!" and "Wassacominago!" in a mock Italian accent in tribute to Chico Marx, with "Tutsi fruitsi" in reference to a sketch in the Marx Brothers film A Day at the Races
Nova Scotia: "Donair!"
Scotland: "Haggis", "Whiskey", "Breenge", "Shortbread", "Shut Yer Face!", "Dumbledore", "Bollocks".
Spain: "¡Ay, caramba!"
Sweden: "Girlwiththedragontattoo", "Lingonberry", "Smörgåsbord", and "Gravlax".

The bleeping effect is still used when Ferguson swears as one of his puppet characters, most notably Sid. Occasionally, the pixelization will still appear with silence in place of the usual censored beep.

Whats a come and a go is an omage to Chico Marks of the Marks Brothers. The accent and the phrase are pure Chico.

There are 2 Italian flag phrases - "What's-a-come-and-a-go?" and "Tutsi-frutsi!" - neither of which are actually authentic Italian phrases.
The phrase that comes with the rainbow flag is actually "Uh-oh!"