颠倒黑白 (dian dao hei bai)
This is a commonly used idiom in Chinese Mandarin. It is used to refer to people who blatantly lie.
颠倒 means reversal
黑 means black
白 means white
Therefore, the literally meaning is that one talks about something black as if it is white; talks about something that is white as if it is black.
In a way, it is similar to the phrase: Twisting the truth.
An example would be:
"他们颠倒黑白,真是可恶!“ (ta men dian dao hei bai, zhen shi ke wu)
Which means "They are twisting the truth, how hateful!"