Have 2 large balloons per person (two different colors) and two already cut strings per person (about 18 inches long each). Split the room in two, one side one color, the other side the other color. Have each person tie one balloon to each ankle. Make the strings long enough to prevent ankles from being stepped on. Turn off the lights and turn on the strobe lights and music (“1812 Overture” works well since the balloons popping sound like fireworks). See which side of the room has more balloons left of their color. Have music to play as they put the balloons on their ankles. Think through the best way to distribute the string and balloons.