Before the Swedish-based chain of humongous home-furnishings warehouses planted its distinctive yellow-and-blue flag on this continent in 1985, who knew coffee tables had names like hajom, rexbo, and axamo? Who knew couches and cruets and wrought-iron curtain-holding thingamabobs could be so cheap? Now Ikea-the antidote to conspicuous consumerism, the budget-minded twentysomething shopper’s home-decorating source-has also become a chic no- frills Hollywood venue for people whose clout is traditionally measured by frill size. Stars (among them Kevin Costner and Farrah Fawcett) browse for CD racks and scatter rugs; the cast of Bodies, Rest & Motion (about budget-minded twentysomethings) held its movie wrap party at the Burbank store; and in NBC’s fall sitcom The Second Half, comedian John Mendoza will shop for divorced-dad furnishings at an Ikea look-alike. His cool acquisition: a woman he meets in the aisles. His cheapo comedown: The bookcase he painstakingly assembles falls apart. But isn’t that part of the frill-free fun?