Shibboleth
Noun: A phrase, word or custom that distinguishes one group from another.
Examples: “Shalom” is a shibboleth for Jews. “Allah Akbar” is a shibboleth for Muslims. “Howdy” is a shibboleth for Texans.
There is a biblical story about the use of a shibboleth to identify the Ephraimites.
The photo is one of the continuing series of Zelensky fan boy photos. this one is from a wood workers shop in the Italian Alps.