唱白脸 Wear the white mask of the villain
【注音】chàng bái liǎn
【解释】你如果看过京剧的话，一定注意到了，“坏人”往往化妆成白脸。所以“唱白脸”表示对人及其严厉苛刻。（常与“唱红脸”一起用，见“唱红脸”）
If you’ve ever seen a Beijing Opera, you’ll surely notice that “villains”would always wear a white make-up. So this expression means you pretend to be harsh and severe. (often used in contrast to “wear the red mask of a hero”, see chang hong lian)
【例子】
例：在我们家，教育孩子的时候我唱白脸。
Ex.：In my family, I’ll play the harsh guy in educating our child.


        
唱红脸
Wear the red mask of a hero
【注音】chàng hóng liǎn
【解释】京剧里的“好人”大都是红脸。唱红脸就是对人显得态度和善。（常与“唱白脸”一起用）
Again in Beijing Opera, heroes normally wear red make-up,so this expression means you pretend to be generous and kind. (often used in contrast to “wear the white mask of the villain”)
【例子】
例1：别看那个老头态度不错，其实他是在为他们公司唱红脸。
Ex1.：Don't look at that kind attitude of the old man, actually he is trying to play the good guy for his company.

例2：一个唱红脸，一个唱白脸。
Ex2.：One coaxes, the other coerces.