早已忘了什么是真心
[zăo yĭ wàng le shén me shì zhēn xīn]
Literal translation is 'Long ago forgot what sincerity means'. By calling themselves such, it might imply jadedness, having lived through too many insincerities that have caused disillusionment, especially in the context of human relationships. Alternatively, this can also refer to growing up process in modern society.