Pennsy Pinkies were introduced during my childhood, in the sixties, so it’s clear that kids from the fifties and earlier would not know them. I remember how excited I was when I was told that there were these great new balls that were better than spaldeens. They did have the Pennsylvania keystone symbol on them. “Hindu” was the do-over term specifically for when the ball took a really bad bounce because of a rock or something on the ground. I found out the derivation of the term when a kid from out of town, during a handball game in the schoolyard, called “hinder” when the ball hit a rock on the court. That told me that the word referred to a hindrance on the playing field.