During the bloodiest years of Mafia violence in Sicily, parents used to reassure their children by telling them the organization only killed in summertime. It's what Pierfrancesco Diliberto, aka Pif, an Italian satirist, grew up hearing. Now he's used that as the title for his film, a comedy about the Italian Mafia. He told Dany Mitzman why he decided to use comedy to talk about tragedy.