Shibboleths are words or phrases that show if someone is part of a certain group or not.
Shibboleths can be important for some groups, but they can also make some people feel left out.
Examples:
The secret handshake was a shibboleth for the club.
Knowing the password is a shibboleth for the group.
She didn't know the shibboleth, so they didn't let her in.
Wearing the right color is a shibboleth for the team.
In some schools, the way you talk can be a shibboleth.
The special hat is a shibboleth for the group.