我姓刘,每次去星巴克买饮料店员都会在杯子上写刘&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;R 请问那个R代表什么