I was a relative newcomer to the US. As a Catholic priest, I was hearing confessions.
A man came in and explained he came to me rather than the other priests because he had Mennel Disease, so I would understand his situation better.
Well, I know that new diseases are being discovered regularly and typically named after the doctor who first describes them.
Alas, I'm thinking, I never heard of Dr. Mennel.
"I'm not familiar with that one," I apologized.
"Really?" he said. "It's pretty common."
"It must be something new," I said.
"No, it has been around!" he insisted, incredulous. Then he exclaimed, quite disappointed: "I thought you were a psychologist!"
Suddenly it dawned on me. He was not talking Dr. Mennel. He was talking American English.
"Oh, you mean mental disease?! Yes, I know about that!"
That was quite embarassing. I had heard Americans assimilating the nt into nn before, plus it is a fairly common phenomenon in the evolution of languages (e.g. Sanskrit dharma compared to Pali dhamma; or Latin doctor became Italian dottore).
But he got me on this one! I was glad when he came back the next time. I was worried I might have lost all credibility in his eyes. Luckily, I did not. Whew!