尼姑阿你和尚阿我
[ní gū ā nĭ hé shàng ā wŏ]
In Chinese, nun refers to a woman dedicated to religious service and monk refers to a male equivalent; this nickname implies 'Nun for You and Monk for Me'. In ancient China, there were many stories about monks who were forced into religion against their will or nuns pining for worldly pleasures which this name evokes. Alternatively, it might be an off-handed jest referring to two people who are very different but somehow paired together.