One player spins a coin and players try to keep the coin spinning by a finger stroke in turn.
The player who cannot keep the coin spinning makes his/her hand into a fist and places it on the table.
The other player takes a heavy coin (an American quarter, for example), puts it flat on the table then flicks it with as much force as possible at his/her opponents knuckles.
The game continues with the player in pain spinning the coin again.