An example of a Hebrew root in English, a shibboleth is a word that only natives can say properly and thus identify themselves as friend and not an enemy. Examples of shibboleths include the pronunciations of the words coax and Williamette (river). Electrical people say co-ax, not coax while Oregonians say wil-lam-it, with accent on the second syllable. On a practical note, during the Battle of the Bulge, American soldiers asked questions about baseball to discover which of the MP’s were actually dressed up German soldiers. For these Germans, a simple question about who played center field for the Yankees proved that they were imposters, just as in the biblical story of saying the word shibboleth.
In fact, the understanding and appreciation of a certain sport is a cultural portal never passed by many immigrants even after decades of residence in a country. These sports include baseball in America and Japan primarily, cricket in England and its colonies, petanque in France, sumo wrestling in Japan, and biathlon in the Scandinavian countries, to name a few.
Not all sports are so localized. Football, soccer in America, has taken root everywhere. It is hard to find a country that does not have a national football team, however incompetent. American football shares enough with its distant cousins, rugby and Aussie football, to be understood by a wide variety of people. Also, its basic attraction, crude violence, is universally appreciated. The relatively simple rules of basketball as well as its ability to be played by people of all ages have made that sport a successful import to most countries.
The telling sign of a sport-culture shibboleth is the demographics of its avid spectators. Looking over a crowd of 50,000 people at a U.S. baseball game or U.K. cricket match, it would be safe to assume that vast majority of the people grew up in that country or another country where the game was played. The number of late converts is probably extremely limited. They have better things to do with their time, which means that they are simply not completely native. That is the magic of a shibboleth.