闺蜜下辈子做我的男人
[guī mì xià bèi zi zuò wŏ de nán rén]
It is a humorous or playful take on wishing one's best friend (usually refers to women who are really close friends) were a guy so they can be together romantically in another lifetime. This could come from deep admiration of a very close female friend or an amusing way to express the strength of female companionship beyond conventional relationships.