眼泪就像大姨妈痛了就来了
[yăn lèi jiù xiàng dà yí mā tòng le jiù lái le]
This nickname expresses the feeling of inevitable and uncontrollable emotional pain, similar to how menstruation is a recurring and unavoidable physical phenomenon. It reflects the idea that sometimes emotions can't be controlled and will naturally come out when someone is hurt.