Me and Julio Down by the Schoolyard

Some interesting comments. I don't think it's about any particular focus so much as teenage rebellion. What the mama actually saw doesn't really matter as much as it was against the law. The two kids could have been messing around, drinking, handling stolen goods (petty theft is sometimes a teenage dare), but they were pushing the boundaries and breaking the law. Mama spits because the narrator, in here eyes, has corrupted her child (in reality they might have been equal partners). Every parent knows someday children lose innocence and adolescence is that period where the children themselves begin to force the issue with experiment. To the parents it can seem like the Apocalypse, they just hope no harm is done during the transition. Of the narrator, he knows he crossed the boundaries and is about to pay; papa wants to put him in a house of detention and he's on his way to one, "taking his time", serving his sentence, ruefully looking back at the familiar, the place and friends he's leaving, "goodbye Rosie, Julio, the schoolyard".

In general the song is pretty upbeat so I'm guessing the sentence is a pretty short one in a juvenile correction center. It's like a rite of passage in someways where innocent world of the child, the rebellious one of the teens is bent back into shape and the conformity of adulthood. Back in the day it was written that conformity would have probably shaped as a blue collar job, a wife, family of his own, the world Springsteen paints in My Hometown before the factory shuts....

Not claiming that's definitive, just a few ideas.