The gamemaster and two players are in the room
Player A gets now a guideline and has to improvise a monologue straight away. Player B watches that. Then player A, the one who gave the monologue, leaves the room. Player C, who was waiting outside, now enters the room and takes the position of player B. Player B, who has just been watching, tries now to repeat the monologue just as he has seen it from player A (including gestures and facial expressions). Player C watches him. Afterwards, player B leaves the room and player D comes in. Now player C holds the monologue, etc.
At the end, Player A comes back to the room and watches the monologue, now given by the last player. Afterwards, he can inform the others, together with the game master, which details have changed — what was newly added, and what was left out.
An exercise which trains precise listening/watching, adopting the smallest details, and copying figures. Furthermore with this practice you realize the details you have forgotten and the ones you improvised credibly.