In this game the players improvise a dialogue along the lines of the famous "Quelle Coincidence!!" dialogue in Eugene Ionesco's "La Cantatrice Chauve" (see the opening lines below).
In pairs, one person initiates the conversation as if it is the first time s/he is meeting the other. The first line is, "Haven't I met you somewhere before?"
In the spirit of "yes, and...", the second person agrees and adds some new detail, e.g., "Yes, I was thinking the same thing, maybe at the horse track?"
The first person accepts the idea and adds a new detail, e.g. "Well I did go to the horse track in New Jersey before, but I stopped years ago."
The dialogue continues in the same way, each time homing in on the details until the inevitable conclusion is reached: the two people actually know each other very well. (In Ionesco's play, are husband and wife, but they can be siblings, colleagues, comrades, even the same person.)
It may be possible to do using famous historical or fictional figures, if the players share enough knowledge to pull it off -- e.g., Lenin and Trotsky, or Diego and Frieda, or Dorothy and Toto...
The challenge of the game is to practice "yes, and" accepting the other person's additions and then adding a new detail, and to hone in on the final result without getting there too quickly.
Example:
Person 1: "Haven't I met you somewhere before?"
Person 2: "Yes, I was thinking the same thing, maybe at the horse track?"
Person 1: "Well I did go to the horse track in New Jersey before, but I stopped years ago."
Person 2: "What a coincidence! I stopped going five years go, just before they built the new club house. But I used to go only on Fridays."
Person 1: "Me too! Nearly every Friday!! My wife and I, but we usually missed the first race, because of the commute from Albany."
Person 2: "No! Albany?! My husband and I used to commute from Albany too! The 7:25 train, car four."
Person 1: "No way! That's incredible!! That was our train and our car too, every week, like clockwork! Seats 12 J and H, by the window.
Person 2: "Impossible!! Unless... Could it be? Are you... my husband? Alfred?"
Person 1: "Oh my God!! Cecille!!"
Fin
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Ionesco's dialogue, from http://www.regietheatrale.com/index/index/thematiques/auteurs/Ionesco/Eu...
( Mme et Mr. Martin s'assoient l'un en face de l'autre, sans se parler. Ils se sourient, avec timidité ).
Mr. MARTIN. — ( Le dialogue qui suit doit être dit d'une voix traînante, monotone, un peu chantante, nullement nuancée ) Mes excuses, Madame, mais il me semble, si je ne me trompe, que je vous ai déjà rencontrée quelque part.
Mme MARTIN. — A moi aussi, Monsieur, il me semble que je vous ai déjà rencontré quelque part.
Mr. MARTIN. — Ne vous aurais-je pas déjà aperçue, Madame, à Manchester, par hasard ?
Mme MARTIN. — C'est très possible. Moi, je suis originaire de la ville de Manchester ! Mais je ne me souviens pas très bien, Monsieur, je ne pourrais pas dire si je vous y ai aperçu, ou non !
Mr. MARTIN. — Mon Dieu, comme c'est curieux 1 Moi aussi je suis originaire de la ville de Manchester, Madame !
Mme MARTIN. — Comme c'est curieux !
Mr. MARTIN. — Comme c'est curieux!... Seulement, moi, Madame, j'ai quitté la ville de Manchester, il y a cinq semaines, environ.
Mme MARTIN. — Comme c'est curieux ! quelle bizarre coïncidence ! Moi aussi, Monsieur, j'ai quitté la ville de Manchester, il y a cinq semaines, environ.