笑看小三说小四贱到无耻
[xiào kàn xiăo sān shuō xiăo sì jiàn dào wú chĭ]
Laughing at how 'The Third Party' ('Xiaosan') talks about 'The Fourth Party' ('Xiaosi'), showing their despicable behavior. 'Xiaosan' refers to a third party involved in someone else's relationship, while 'Xiaosi' suggests an even more extreme level of interference. It mocks infidelity in a sarcastic way.