There's an Irish Rovers song we used to sing as kids while playing around but it refers to an Irish or Irish-American term for policemen "peelers". I think it's The Man from Mullingar.

Peelers is a pretty common slang term for cops in my ethnic group even among those of us from law enforcement families. I don't recall ever getting smacked for it they way we might have for using American slang for cops such as "fuzz". of course, none of us ever called a cop a "pig" unless he was a close relative who had done something disgusting !