“Do you like my tail?” Hermès chairman Jean-Louis Dumas asked last Tuesday night in Paris. Dressed as a tuxedo-wearing squirrel to celebrate the luxury firm’s 2004 theme —color and fantasy — he hosted a costume ball peopled with pirates, popes and powder-faced libertines. Asked why he chose the animal costume, Dumas said, “Because I love hazelnuts.” Not everyone dressed as extravagantly. Richard Buckley, arriving in a black turtleneck and pants and white bunny ears, was offered a fluff of white feathers by Suzy Menkes. “Attach this to your butt,” she instructed. Philippe Starck’s getup wasn’t obvious either. He said he was “the Turkish Mafia boss” from the movie “The Usual Suspects.” After a three-course dinner of lobster and squab, Hermès sent out tap dancers, folk singers, a swing band and a 15-foot ostrich to fuel the fantastical fete. But the fantasy line of the night went to Hermès’ Stephane Wagnier, who was wrapped up in a big Hermès box. “I’m on sale!” he declared.