SQLite Adopts 'Monastic' Code of Conduct (sqlite.org)
Having been encouraged by clients to adopt a written code of conduct, the SQLite developers elected to govern their interactions with each other, with their clients, and with the larger SQLite user community in accordance with the "instruments of good works" from chapter 4 of The Rule of St. Benedict. This code of conduct has proven its mettle in thousands of diverse communities for over 1,500 years, and has served as a baseline for many civil law codes since the time of Charlemagne.
Not everyone has found SQLite's attempt informative or funny (though many did). A developer wrote, for instance, "So is the SQLite CoC thing a joke or not? If it's not a joke, f*ck this. If it is a joke, that's even worse. Your CoC should be taken seriously." A security researcher, chimed in, "This sort of stunt will make actual code of conduct discussions harder. It's not funny, helpful, or wise."
Shibboleths are things that are useful for identifying distinct groups of people. A good example is the bar scene in the Tarantino film Inglorious Bastards. One of the characters is an Englishman pretending to be a German Officer and he does an okay job, especially given the tense situation and everyone is fooled. However, the hand gesture he makes when ordering drinks is improper and immediately betrays him as a spy.
The word itself comes from an old Hebrew word that has an unrelated meaning to the present use, which springs from a Biblical story, where the word "Shibboleth" was used as a modern shibboleth because it was pronounced differently between two warring groups and could be used to tell if a person was a foe attempting to pass themselves off as a friend. There are plenty of other examples of this being employed throughout history. For example, if you're traveling in warn torn parts of the Middle East, you may want to memorize a few passages from the Quran as that's a common shibboleth used by militants to determine if someone is actually a Muslim since it's often impossible to know based on appearance alone.