笑来了大姨妈哭来了大姨夫
[xiào lái le dà yí mā kū lái le dà yí fū]
This nickname is a colloquial and somewhat humorous or awkward expression used to indicate that emotions (like laughter or tears) come unexpectedly and uncontrollably, sometimes compared to how menstruation comes, as an idiom for something inevitable or suddenly happens.