تعریف و معنای "[have] {sb} by the short hairs"

What is the origin of the idiom "have someone by the short hairs" and when to use it?

The exact origin of the idiot "have someone by the short hairs" is uncertain. However, it is believed to have its roots in the idea of physical control or manipulation. The phrase metaphorically refers to having a person grasped or controlled by a sensitive and vulnerable area, such as the short hairs at the back of the neck, which are difficult to escape from without resistance. It is often used when discussing power dynamics or relationships where one individual holds leverage over someone else.