Kids love to do that.
Tradition says one should keep one chestnut in the pocket against rheumatism.
We used to keep a large wild one in our pocket to get warm hands in the winter.
When you rub it against your trousers it get's shiny, but warm too.
You can even rub it too long and burn your hand when you're not carefull.
My kids like to do what I did when I was young: take a handful of chestnuts to school.
When you're hungry they're good food.