One house. Forty strangers. Add vodka and stir . . . Every summer, scores of Manhattan twentysomethings take part in an annual ritual with a camp-like culture distinctly its own: the Hamptons sharehouse. When Rachel and her two best friends buy their shares for twenty times each of their bank balances, they're imagining days filled with lazy suntanning and classy clambakes and nights spent rubbing shoulders with the Olsen twins and other celebrities...