柳色堪折
[liŭ sè kān zhé]
'The green color of the willow can be broken off' originates from ancient times in China when people would send their friends off by parting them ways beside a riverbank where the willows were growing. 'Bringing a willow sprig' implied the unwillingness to depart, because 'Willow' sounds like 'staying'. So, this online nickname expresses nostalgia for someone special who's no longer close.