你是我最好的姐妹你是我最好的闺蜜
[nĭ shì wŏ zuì hăo de jiĕ mèi nĭ shì wŏ zuì hăo de guī mì]
In Chinese culture, siblings or close female friends can be very important to an individual. This nickname emphasizes the importance of this friendship and conveys that the friend is as significant as any blood relative. A way to say the closest friend is regarded just like family, showing great value on the friendship.