First ask everyone not to talk. Then blindfold half off them and have each blindfolded person sit next to an empty chair. Those who are not blindfolded sit in the empty chairs. So every blindfolded person sits next to a person that is not blindfolded. Starting with the first pair, have the person who is not blindfolded sing a short song in a disguised voice. It is up to the blindfolded person to determine who the person that sang was. If they guess correctly they can remove their blindfold, if not they must keep it on. Then the next couple then go. After each couple has had their turn, the ones who are not blindfolded and have not been identified move around and exchange seats. The last one who isn';t blindfolded left over at the end wins. The players who were blindfolded then swap with those who weren';t.
Source: From the original site.(Submitted by: Gavin)