Name swapping game
The Sofa Game. You need two teams. The aim of the game is to get three of your team sitting on the same sofa/bench. Everyone writes their own name of a slip of paper, then shuffle them and each person takes one. You then 'become' whatever name you are currently holding.
The sofa in question starts off with one person from each team and a space, everyone else needs somewhere to sit round the room.
The person to the left of the space says a name, and whoever has that bit of paper moves into the space, and swaps with the caller. This frees up another space somewhere in the room, and whoever is to the left of that space calls a name, and so on....
Because everyone swaps names all the time it is very difficult to keep track of who is who, and much hilarity results.