Speak Like a REAL Chinese Mandarin Slang Vocabulary of Relationship Learning 03Cheating video learning resources Instagram: ngchinesehk How to say cheat in relationship in Chinese? Some people said: 骗piàn. This means to lie to someone, but this only means not telling the truth. We have a special term for cheating in relationship: 出轨chū guǐ. Originally this is an action, used as a reference of the situation when a train goes out of the original railway, but now, people use this as a reference of cheating in relationship in Mandarin. If you want to say he cheated on her, you can say: 他出轨了tā chū guǐ le. Another thing you need to know is: 戴绿帽dài lǜ mào, put green hat on. What does that mean? It also mean to cheat on her (see video on Instagram for the explanation), 他给他戴绿帽tā gěi tā dài lǜ mào means he cheated on her.