I got this from Kani Club, the improvisation school in Tokyo. It is a great "Yes, and..." game.

Pairs or trios (daunting to do in larger groups, but could be done with practiced players).

The idea is for the players to speak a sentence simultaneously without knowing what the sentence will be ahead of time, relating the sentence to some physical action or pantomime.

For example, one player could begin to reach up. The others reach too and give the reach some new quality (a grimace, a hopeful look), which the first player also takes on. As this happens, the players also start to speak their line, carefully watching the other players, their expressions, mouths, actions. Ideally, the players will articulate the line together, in synch. E.g., "This apple is mine."

The game requires concentration and exacting observation. It is fascinating to see how the initiative flows among the players, who alternately lead and follow, always in the spirit of "Yes, and..."