Every Jew that I know is familiar with the game of "Jewish geography".
The game is played as follows: two Jews meet anywhere in the world. Often it is as guests at some mutual friend's shabbat table for lunch, or after spotting a kippah on vacation in some remote area.
The two start talking, and the first player says where he or she was born/grew up/went to school/went to camp/worked at/lived in/etc. The second player now goes "Oh! Do you know so and so? He/she also lived in/went to/worked at/etc."
The first player denies knowledge, and then asks a similar question to the second player. This continues back and forth until a mutual acquaintance is found. Bonus points now accumulate as more and more acquaintances are found, using the first match as a branching point.
The game always works. I mean: it always works. Well, ok, not always, but close enough.
I'll tell you two of my own stories:
I was in Hartford once, at a one day meeting of Pardes Institute alumni. My wife at the time was an alumni, while I didn't know anybody. Sitting on my left was my wife, on my wife's left was some guy whose name I don't remember (let's call him Phil), and on my right was some guy named Eli.
I was introduced to and became friendly with Eli. He is an amusing, but highly cynical young man. We're talking and I hear Phil mention to my wife that he once worked for the ADL, an organization that fights against racism and anti-semitism in America. It must have thousands of volunteers across the country.
I lean over my wife and ask Phil, "Hey! Do you know Joe?"
On my right, Eli's eyes bug out of his head. "Do you know Joe?" What kind of question is that?
Of course, Phil says, "Yeah! I know Joe. Great guy!" And yes, we were both speaking about my friend Joe Nathan, who had volunteered at the New Haven branch of the ADL one year.
I went to Cornell, and a friend of mine there spent her Junior year in France. She went to England for one weekend, and ended up at a Chabad house for one meal. Across from her was a young English student named Danny.
When she mentioned that she goes to Cornell, Danny says, "Oh! I know a guy who goes to an Ivy league school in America. Perhaps you know him?"
My friend thinks to herself, "Right. Sure." "Who?" she asks.
And it was me.
Now, those two stories are extreme examples. But even without the examples, the odds of finding a match are actually very high. Why?
First consider that the participants are identifiably Jewish, and in my situation, religious. That already narrows the world down to about two million people.
Now consider that religious Jews always make many acquaintances, since they almost always belong to local synagogues. There are only a few thousand synagogues in the world, maybe tens of thousands.
Now also count that fact that we are dealing only with the English speaking Jewish population, because that is who I am going to play the game with.
Any Jew traveling anywhere is going to stop into the prominent Jewish area of wherever they are traveling. Either it is to find the one kosher food market, daven in the local synagogue, or get invited to a local family for a meal.
All Jews travel in spokes from the main Jewish axes of the world, which include New York, Chicago, Los Angeles, Memphis, Miami, London, and especially, Israel. All Jews going to Israel have gone to the Western Wall, Yad Vashem, the central market. The odds of having met the same people who are at these locations every day are extremely high.
The Social Genome
The truth is that this works for many other groups of people as well. In fact, I would venture to say that it probably works for most people.
It used to be that we all liked the same music, watched the same TV shows, and read the same books. Many people saw this as something positive: this common sharing of culture works as a social lubricant when we intersect.
On the other hand, it also genericized all of us as strangers. If the whole world listens to the same piece of music, then any two people have no particular sense of kinship. They don't stand out from others.
Jews form cultural connections because of their very differentness from the societies they live in. This separateness from the masses creates a kinship with others in the same group. If a billion people like "I Love Lucy", they don't feel a connection. If two people like "Ishtar", they are now connected in a special way.
Nowadays, as mass cultural touchstones become less frequent, and we all begin to like niche bands, movies, and books, paradoxically our sense of kinship with others begins to grow. There's little kinship between Britney Spear fans. There's a lot between Lynn Miles fans, because there are so many fewer of them.
But each person likes more than one thing. Consider a person who likes:
100 different niche bands
100 different niche books
50 different niche TV shows
Not to mention our continuing touchstones around towns in which we live, schools we attend, religion, and so on.
That's a lot of niches. Think of each person's likes as genome tags sticking out from them. Any intersection with another person, on any of these likes, creates a kinship. This is why MySpace works so effectively.
This is also why the old theory of "Six Degrees to Kevin Bacon" works so effectively. The number of possible contact points grows exponentially as you branch out.
Nowadays, I feel kinship with board gamers around the world. I'm sure many of them would invite me to their home simply based on this connection. If it wasn't board games, it could be a special movie connection, or any other forum topic.
So long as the familiarity is there, and you have distinguished yourself as having basic civility, anyone should be able to play the geography game.
Oh, I forgot to add: this subject came up because I played it last night. I met someone on the street, and it turned out that they now play Settlers of Catan because they play with someone to whom I introduced the game many years ago. She bought a copy through me, and is now teaching her friends, of which he is one.