No, I never knew just what it was, and I guess I never will. 
Sounds marvellous, though.
Speaking of which, I actually think that’s a brand name for two spheres (not lucite aka plexigass, more like stone), with a string connecting them, and a ring to hold on to… but the set I had, in roughly 1983, had some sort of GUNPOWDER on the outside, which made the “clack” sound much more pronounced, and would even cause a spark and leave a smoke trail.
Of course, after several hundred “clacks”, the explosive coating wore away and they became normal “clackers”.
Upon Googling, I see that the name “kerbangers” is not a trademark… and was indeed used by many companies selling the child’s toy.
Anybody remember what I’m talking about? These would cause a mini-explosion, which, either real or perceived, produced MORE energy than mere elasticity.
They also had burn marks on both spheres from every “clack”, and wore out quickly, becoming normal “clackers”.