日防夜防大姨妈难防
[rì fáng yè fáng dà yí mā nán fáng]
In this net name, a funny and somewhat helpless situation was conveyed about menstrual issues ('Big Aunt' is a colloquial term used humorously in Chinese to refer periods), suggesting that even if you are vigilant during the day and at night but some things cannot be avoided like monthly menstruation cramps, bleeding days for women.