It was a typical night at Koi in Los Angeles. Mariah Carey was there. And Serena Williams. And Rick Fox, the former NBA star and ex-husband of Vanessa Williams. Interspersed among them were clusters of skinny women picking at their spicy tuna—except at the bar. There, sporting jackets of indeterminate materials, sat a row of men with remarkably thick necks. Meet the bodyguards. These intimidating specimens have become commonplace everywhere from Melrose boutiques to exclusive Upper East Side restaurants. “So many people are trying to make a statement by hiring bodyguards,” says Josh Woodward, owner of the trendy Table 8 restaurants in L.A. and Miami. “They want the stares and the whispers. It’s ostentatious.” Herewith, six rules of etiquette that separate the good behavior from the gauche.