It’s the name/game given to chestnuts where you put a hole through the chestnut and pass some string through and tie it off.
The game is simple you try and break your opponents conker with yours. Taken turns.
The defender holds the string steady with his conker straight down
The attacker uses his conker to try and break the defenders using a sort of downwards flick.
Ahhh, I finally understand trickle down economics.