你若长裙落地我必短裙相配
[nĭ ruò zhăng qún luò dì wŏ bì duăn qún xiāng pèi]
It translates to, 'If you wear a long skirt that drags the floor, then I will match you with a short skirt.' The underlying idea is mutual agreement or matching with someone else or some event, showing readiness or adaptation.