The venues are kept secret to bamboozle the police, and the guests are told where to go by text message. But the latest underground movement sweeping Italy has nothing to do with drugs or dance music: it is fuelled by home-made sausages, mouth-watering risottos and freshly baked bread.
Fed up with the high cost of eating out, and the recent ban on smoking in restaurants, Italians have taken to organizing illegal private meals, charging 15 euros (US$18) a head for parties of up to 40 people.
`fai da te'
The authorities have taken a dim view of the practice -- known as "fai da te," or do it yourself -- because the hosts avoid paying taxes and sidestep health and safety rules that restaurant owners have to abide by. It is also illegal to charge people for food cooked in your own home. However, that has not stopped the movement.
The trend started in Milan with groups of young people organizing do-it-yourself restaurants in private clubs or halls and apartments. In the past few months, the phenomenon has spread and "private trattorias" are springing up in central Italy.
According to the Corriere della Sera newspaper, they have become popular because of the dire state of the economy. Many Italians cannot, or will not, pay to eat out any more because prices in restaurants have soared since the introduction of the euro.
Groups of young Italians have been the driving force, the newspaper says, and all that is needed is a venue, such as a country house with a large wood-burning oven and a barbecue.
Once the number of customers is known, the group of amateur cooks devises a menu and brings dishes, cutlery, pots and pans.
"Depending on the type of clientele, the evening's entertainment might just be people sitting around talking after dinner or they might dance and have music," says Luca Goldoni, who has attended such evenings. No one protests, he says, because in summer they usually take place in isolated spots in the country.
The menu for one of the meals included home-cooked antipasti of salumi (cooked meats) with freshly baked bread, asparagus risotto, chicken with olives or wild boar stew, followed by freshly picked peaches with ice cream.
Entertainment is provided by someone who plays a guitar or accordion, and people can smoke freely and remain at table until the small hours.
Organizers of a private trattoria can make significant amounts of money. Forty people paying 15 euros a head means a take of 600 euros an evening. Ten such evenings a month adds up to 6,000 euros.
The Italian authorities point out that, as well as the tax evasion issue, it is against the law to charge people for food cooked in a private home.
Real restaurants also have to undergo hygiene inspections, are subject to health and safety regulations and have to pay for insurance cover and properly trained staff.
The police have said that anyone setting up a private trattoria will get a warning but will face prosecution if they continue.