I worked in a shop where we played a game called Chino. Everyone started with 3 coins in their left hand. Each transferred 0, 1, 2, or 3 coins to their right ha

I worked in a shop where we played a game called Chino. Everyone started with 3 coins in their left hand. Each transferred 0, 1, 2, or 3 coins to their right hand and extended their closed right hand. Each made a unique guess of the total coins. A correct guess wins the benefit or liberates the guesser from subsequent rounds to determine who had to do the dirty work. Modified for your situation, each would agree to have 0-3 coins when you meet. The total could pass for a pseudo-random number.