As part of the Artificial Language known as Thieves Cant it is a term used to describe the local Chief of Police. Origins as near as can be tracked down, are based on the term Pig as it is used to describe the Police and was modified by Cockney wiseboys. English only--in other languages the term is replaced with its equivalent in that language.
Example: Papa Porker's outta town, me and my fence are going to go pickin' bits at the trough. Which translates to: The Chief of Police is not in town, me and my watch (lookout) are going to go steal from the police station.