They said he had balls of steel to try that one For the yanks and elsewhere, yes conkers is well known in Britain. You basically put a chestnut (but its a conker) on a string by making a hole in the middle. Take turns swinging them on the string, whoever's breaks is the loser. It used to be great fun till it was banned/requires eye protection now. There's an opportunity there, someone could make a perfectly safe conk…
How is it banned? Banned in schools you mean? Because I can’t see how authorities could ban anyone from picking up a conker from the ground and tying a string to it. On a different note, if you’re just pulling a random one out of a bag, what is the competitive aspect? Is there a technique involved? Or just RNG?
Believe it or not adults playing conkers or people playing conkers outside of schools isn't a common pass time.
It is pretty much RNG, though you can massively nerf a conkers structural integrity by making the hole through the middle poorly, so there are some techniques. People also used to use thicker shoelaces like in vans, which I think made the centre more solid. I've never run an experiment to verify the difference that might make.