1. I’m not very good at understanding the directions on how to assemble these modern-day toys. They’re all Greek to me.
2. Can you tell me what this page says? I don’t even know if it’s right side up or upside down. It’s all Greek to me.

The expression can be traced back as far as Shakespeare’s play Julius Caesar , and probably originates from the idea that the Greek language uses a different alphabet from English, making it difficult for English speakers to hear or understand.