This allusion is described by the phrase “sheep skin and tiger skin”, which means that although it looks good on the outside, it is empty and impractical inside. A relatively simple and complete explanation is as follows: used to metaphorically refer to a person who is covered with a false and deceitful appearance, but in reality is an empty and powerless person. This idiom has a very wide range of applications, such as the scoundrel in the market, who usually acts arrogantly and bullies kind people. When the bullied person can no longer bear it and wants to fight against the scoundrel, the scoundrel actually shrinks back and runs away. This kind of scoundrel who bullies the good and fears the evil can be said to be a “sheep’s skin and tiger’s skin” person.
这个典故，被大家用“羊质虎皮”这句话来形容，表示外表好看，里面却空虚而不实际的意思。比较简单而完整的解释是这样的：用来比喻蒙上一层虚伪欺人的外表，而实际却是一个空虚无力的人。这句成语应用的范围非常的广泛，像市井中的无赖，平日作威作福，专门欺侮善良的人，等到被欺侮的人忍无可忍，要和这个无赖拼命的时候，无赖反而畏缩逃走，这种欺善怕恶的无赖，就可以说是“羊质虎皮”的人。
《古代寓言·羊质虎皮》
羊质而虎皮，见草而说，见豺而战。忘其皮之虎矣。——《法言》
The Lamb in a Tiger’s Skin
Once a lamb clad itself in a tiger’s skin.
As it was stalking along, it bleated joyously at the sight of the green grass, but when it saw a wolf in the distance it trembled all over.
The truth is that the lamb had forgotten that it had the tiger’s skin on
