One of the players tells the story of the Pony Express, and how the messenger-riders had so little time that they never touched the ground when changing horses but jumped from on horse to the other. "Horses" are spaced out over the course the smallest player in each group is the messenger. Any messenger touching the ground on the change-over from one player; to another must start over. First player finished is the winner.
Pair off the horse and rider teams. On command, all riders change horses without touching the ground.