花开了又谢可你在哪
[huā kāi le yòu xiè kĕ nĭ zài nă]
It refers to time passing ('Flowers bloom and then they fall'), which implies missing someone. It's like saying 'Where are you? The flowers bloomed again this season but it feels meaningless since I can't find you'. This nickname expresses the loneliness and melancholy due to the absence of someone important.