Group challenge. Give everyone a number. They have to arrange themselves in numerical order communicating with each other without speaking their native language or holding up fingers. They can make up their own sub-language or sign-language and it is often pretty amusing.
Round two. Have people arrange themselves in order of birth or in calendar months.
From a educational point of view this would a useful game when teaching languages and only allowing communication to be in the language you are trying to teach. by