The word "狈" in the idiom "coulter" refers to a mysterious animal with a dog's head and human body in northern legends. In ancient Chinese literary works and legends, Nong is often depicted as a monster with a dog's head and body, and is usually described as vicious and cunning. In idioms, the word "狈" in collusion is used to describe bad people who collude together and describe their ugly behavior.
In modern usage, this idiom is usually used to describe several criminals who collude together, or to refer to people who collude together to do bad things.
