A reference to a person who feels inferior and therefore tries to stress the little bit of authority or power that they hold at every opportunity, in an attempt to impress people around him and to incorrectly reassure himself that the power he has is actually worth something.
It is generally used to refer to bouncers or security guards and occasionally but no where near as often some police officers.

When you eat dirt for the first time and leave your family to build a shack in the woods