旧城以南莫失莫忘凉城以北良人未归
[jiù chéng yĭ nán mò shī mò wàng liáng chéng yĭ bĕi liáng rén wèi guī]
This nickname is derived from a poetic expression that roughly translates to 'In the South of Old City, never lose or forget; in the North of Cool City, the loved one has not returned.' It implies a longing for reunion and cherishing past relationships.