I came across this term used several times in a news article I read today. I had never seen it before, so I googled it and got almost a million hits -- the first several of which were from UNICEF. This leads me to believe that it is the new (or maybe not-so-new, I'm not up on such things) PC term for what we used to call juvenile delinquents.
One of the really hilarious things about do-gooders is that they seem to honestly think that changing words changes reality; that if a thing or situation or group is negatively perceived by the public, that changing the name will change the perception and solve all the problems associated with the thing/situation/group.
It doesn't work, but they keep doing it. What does that tell us about them?