I grew up in Ridgewood, Brooklyn during the late sixties and we used to play Skellsy amidst the street traffic. We never filled our caps with any kind of substance, but my buddy Joe, who grew up in Howard Beach tells me he used to melt crayon wax into his caps for added weight. He and I have debated for years the correct name of this beloved game. He called it skullys and I called it Skellsy. I guess we were both right.