女子不毒妄为女子
[nǚ zi bù dú wàng wéi nǚ zi]
A woman will not get far unless she has been ruthless or unscrupulously competitive. Suggests that without some level of ruthlessness or shrewdness, a woman cannot make significant achievements in society. There’s also an ironic take suggesting that sometimes a 'mean girl' can be seen as empowering rather than malicious.