I'm talking of a certain wit that is characteristic of streetboys and streetchildren in general. I'm not sure if streetchildren is the best way to describe these kids. That might not be very common in developed countries, where few people are homeless or deprived of education and other basic rights like how it is the case in the Third world.
On a more general note, I'm referring to children that are not too pampered and have learned to get on by themselves. Clever, fast, handy, quick to learn, and with a sharp tongue. Think Dicken's Artful Dodger.
In contrast to a spoonfed crybaby who has their parents by their side at all times. Pardon the heavily stereotypical descriptions, but that was just to get my point across. And please do try coming up with something more sophisticated than "street-smart" or the like.
A sample to give you an idea of what I'm getting at:
It was amusing to see how he gave out instructions to the others his age labouring and taking orders. His words were slick, typical of a know-all streetsmarty. The big-eyed kid had been trudging past the shady-looking resturant when that boy with a shabby hat whistled at spotting him. "Ye, looking for work, huh?" He jumped down onto the road and made his way towards the trembling child of four.