Everyone into pairs for an exercise that trains sharing focus, taking focus and physical listening.
One of the players in the pair begins to gradually move. The other player mirrors the movements of the other player. Initially one player is leading the other and then the lead switches. Eventually there is no way to tell which player is leading the exercise the focus is being shared rather than taken by one player or the other. The object is not to screw up the other player, but to make the reality of the mirror the priority.
Try a kaleidoscope with three or more players all mirroring actions in a circle.
Sounds can be mirrored as well.