我要做你唯一的兄弟我要做你唯一的姐妹
[wŏ yào zuò nĭ wéi yī de xiōng dì wŏ yào zuò nĭ wéi yī de jiĕ mèi]
This name implies a deep, all-encompassing friendship, expressing that the person wants to have an irreplaceable sibling-like relationship with another. In some contexts in China, when someone calls others brothers and sisters online, they are usually expressing close friendships or strong camaraderie.