Divide the group into equal teams. Partially fill the balloon with water and give each team a balloon. The team members sit down in straight lines. On “GO”, the first person on each team places the balloon between his feet and, using only his feet, passes the balloon over his head to the next person in line, who receives the balloon, using only his feet. The relay continues until the balloon has reached the last team member (if the balloon falls, it is returned to the first person in line so that the relay can begin again). If the balloon breaks, the team is given a new one!
The first team to successfully pass the balloon to the end of the line wins.