A shit sheriff is a janitor that hangs out in the bathroom while you're dropping a load, usually a really explosive load that splatters the bowl and sometimes gets on the back of the seat. The shit sheriff goes directly in behind you armed with a bowl brush and a grimace.
An annoying person who wants to be a police officer but in reality the only thing they can do is direct traffic in parking lots without being asked to.
Ashley: Hey why is that lady standing in front of cars motioning them to go by in the mall parking lot?