Take as many film cannisters as you have people. In each film cannister, put an object.
The objects you pick can be like the following: cotton balls, pennies, paperclips, jelly beans, m&m's, etc. If you have 30 people and you want to divide them into three groups of 10 each, you would place a cotton ball in 10 of the cannisters, a paperclip in 10 of the cannisters, and a penny in 10 of the cannisters.
Each individual then picks a cannister from a bag, basket or some other container. They can not look or smell in the cannister. They can only shake the cannister to distinquish the different sounds of the objects.
The object is for the individual to find persons in the group with a like sounding object and stay with that group. There are many variations on this game.