Around the same time, maybe a little earlier were knockers, or clackers.. two large hard plastic balls or marbles on the ends of a string, and a ring in the middle.. the idea was to make them hit below your hand, and above your hand.. Also outlawed because the balls would shatter, or the string break and they would fly off and hit someone..
Loved mine, although my arms were one huge bruise from them..
Here's a video if you don't know what they are... looks like someone is making and selling them again..
http://www.youtube.com/watch?v=FLHft...eature=related