The Guardian has had some fun this morning with a piece by Oliver Thring which looks at the slang used by restaurant staff. From HAF to PIA, it explains the coded terms used in some restaurants to describe the customers.
As Mr Thring points out, such code is common in many jobs. Before patients were allowed to see their own records, the medical profession employed a wide variety of shorthand slang to describe their clients.
GPO stood for Good for Parts Only while PAFO related how a patient sustained their injuries: they were P****d And Fell Over.