In Finnish we have “kissanristiäiset” (literally means a cat’s christening), which means some trivial and meaningless celebration/event.
It appears many languages have an equivalent to this, and many like English, point to Greek with “It’s Greek to me” - and the Greek say “it’s Chinese to me” and apparently the Chinese say “it’s heavenly script”. Here’s an interesting chart showing where many languages point for something incomprehensible. Source