班主任就是容嬷嬷投胎来的
[bān zhŭ rèn jiù shì róng mā mā tóu tāi lái de]
This nickname is a humorous and exaggerative comparison. The class teacher (an authority figure in Chinese schools) is likened to Concubine Rong, a strict and often feared character from the drama 'The Legend of Zhen Huan.' The nickname implies that the class teacher is as intimidating or strict as Concubine Rong.