Petra Nemcova turned heads in an eye-popping gold gown at her Happy Hearts Fund gala Tuesday. But guests found the most irresistible guest at the gala — where the theme was “Land of Dreams: Mexico” — to be a cougar cub named Zeus. The cuddly critter was at the Metropolitan Pavilion, where guests got passports and toured displays of Mexican cities with “flight attendants.” Special guest Carlos Slim announced a partnership with Happy Hearts to rebuild Mexico’s schools, and Marc Anthony performed.