
皮(Skin pei4) is important to our body, in Cantonese, there are some idioms which are related to “skin”, like:

厚(thick)面(face)皮(skin)hau2 min2 pei4
Literally, it means to have a thick skin
but it also means shameless.
Eg. He tells his friends that he always pees in the street, I think he is very
hau2 min2 pei4 (厚面皮).
hau2 min2 pei4 (厚面皮).