非礼你媳妇大姨妈根源
[fēi lĭ nĭ xí fù dà yí mā gēn yuán]
A playful and rather informal expression, loosely translated as 'Your period originates from your mother-in-law visiting'. It uses a humorous or provocative reference to a monthly visitor ('big aunt', a euphemism for menstruation) causing disturbance humorously attributed to one's mother-in-law.