My SIL did that in Costco recently. He & my daughter were eating, and noticed they were the only ones speaking English. Several were nodding at them while talking in Spanish, so my SIL (2 tours in Iraq) began talking to my daughter in Arabic.
After he gave a long comment, she asked what one of the words meant. My SIL replied, “That means fat” in a loud enough whisper to be overheard. It didn’t, but he figured no one would know.
There was a dead silence at the tables around them. They finished their food, got up and left.
Love it!