There's something special about the 91-year-old Lexington Candy Shop, a humble luncheonette on the Upper East Side at the corner of 83rd Street and Lexington Avenue. Maybe it's the vintage decor: neon signs, a chrome-accented counter and signed celebrity photos. Maybe it's the 1940 Hamilton Beach milkshake mixer, admired by generations of customers. Or it could be the fact that Lexington Candy Shop still belongs to the family that opened it in 1925.