尺素无端
[chĭ sù wú duān]
'Chisu Wu Duan' is an elegant term. 'Chisu' traditionally refers to letters written on strips of silk during the ancient times and 'Wu Duan' means without reason or unexpectedly. Therefore, this nickname can symbolize sudden thoughts, unplanned feelings, or unforeseen happenings expressed through old-fashioned letter writing.