Justin Timberlake and Nelly Furtado are the worst behaved diners in showbiz, according to celebrity restaurateur GUY RUBINO. Rubino claims Timberlake insisted on ordering off the menu and Furtado acted like a diva during visits to his Toronto, Canada eaterie Rain. The chef tells The New York Daily News, "Timberlake comes into Rain, doesn't even look at the menu and shouts for random food that we don't make. If he knew what he wanted, why come to an Asian restaurant in the first place? "(Furtado) made a reservation for 10 guests. She showed up an hour late with five extra people in tow. For parties that size, we do a prix-fixe type of menu. "Nelly objected and was really rude about it. She expected individual dishes to be prepared. Her manager even came into the kitchen and had the gall to say, 'Just f**king do it! I told her that she and her client could just f**king leave." In contrast, Rubino claims Michael Douglas and Catherine Zeta-Jones were the best guests: "They're very polite. Every time they come in, they pop into the kitchen to say hello. I just love them."