The meaning of a Chinese idiom

Now, in the world many people begin to learn Chinese. The following will help you learn a Chinese idiom. May be it is not used in your daily life but when you have China tours and use what you have learnt, the local people will like to contact with you.
Hiding a dagger behind a smile (笑里藏刀)

In the Tang Dynasty (táng cháo 唐朝), there was a minister called Li Yifu who was always affable and smiling. But in his heart he was very sinister and ruthless. He constantly schemed against people he saw as possible rivals. He was called : The knife in the smile". This idiom, derived from the above story, means disguising a ruthless nature behind a pleasant appearance.
Chinese like to use idioms to express themselves. So even though you can speak the Chinese idioms, you should know the meaning. If you have plan to join a private China tour package, you can ask your tour guide to teach you other Chinese idioms, they will be very helpful.