小三始终是剩货
[xiăo sān shĭ zhōng shì shèng huò]
'A mistress will always be leftovers'. In China, 'Xiao San' specifically means 'mistress' or a third party involved in someone else’s marriage, which carries social stigma. This implies an inferiority complex or societal criticism of being viewed merely as something secondary and undesirable.