小三会被小四替代
[xiăo sān huì bèi xiăo sì tì dài]
This internet nickname 'xiaosan hui bei xiaosi tai da' in Chinese implies a social phenomenon. In an improper relationship, '小三 (xiaosan)' usually refers to the 'other woman' involved with a married man, and here it humorously suggests that even such a position is not secure, as another 'other woman' (小四, xiaosi) might replace her.