Many years ago, I called the home of my Chinese-speaking nieces. This was before they started learning English and before I started learning their dialect of Chinese. After the call was over, the eldest niece asked, "Who was that on the phone?"
"That was Uncle Raymond."
"Oh, I want to talk to Uncle Raymond!"
Her mother replied, "That'd be like a chicken talking to a duck."
A chicken talking to a duck is a Chinese idiom referring to two people who cannot communicate due to a language barrier.
It seems that ducks are somehow central to the concept of language unintelligibility. Is there a duck-related language idiom in your language?