Word clearly Italian, but that has origins from South Italy and more precisely from Naples and the surrounding area.
"Scugnizzo" is a boy who has fun with other friends, spending a lot of time among the streets (vicoli) of Naples.
Currently, it is also used to describe the children, when they are clever and cunning.
Tu sei una volpe! Tu sei veramente uno scugnizzo!
You are a fox ! You are really a scugnizzo!