经痛如此多娇让姑娘痛断腰
[jīng tòng rú cĭ duō jiāo ràng gū niáng tòng duàn yāo]
A somewhat exaggerated expression combining 'cramps during menstruation' (经痛, jīngtòng) and a poetic way of describing pain (from an ancient poem '江山如此多娇'), meaning 'menstrual cramps are so painful it can make a girl feel like she's bent double with agony'.