It is generally used as a slang term to put more emphasis into the word police,
most commonly used by the youth when evading the Law
Cop: Hey you, kid get your ass over here where taking you home
Gurney: it wasnt mine i swear i dunno how it got there.
Nitchskie: Dude Fucking BAIL!
Nitchskie while jumping a fence: FUCK THE PO-LICE!