This happened to me during the summer when I was working in Singapore:
I didn't know anyone so the only thing I would do all day was people watch. I loved it. Anyway, so one day I was at lunch when two women sat down at the table next to mine. One of them had a cute fringe. They had to borrow one of the two chairs from the table I was sitting at, so I felt slightly more self-conscious about eating alone than usual, haha. Before they started to eat, the woman with the fringe asked the other woman to say grace. I watched attentively because public praying has always fascinated me. They both closed their eyes as the woman quietly spoke. However, midway, the one with the fringe opened her eyes wide and stuck out her tongue, waiting for the non-fringed woman to open her eyes. When the non-fringed woman finished saying grace and opened her eyes she noticed her friend. They both laughed loudly and, mortifyingly, so did I. It was one of those laughs that you think you can hold in, but escapes at the last second. I froze. I was horrified at being caught eavesdropping, or in this case, spying. But when the non-fringed lady turned to look at me, she smiled, gestured at the fringed woman, and said, "Haha, she's so naughty!" The word choice struck me as odd, but I was just relieved that they weren't weirded out by me, hahaha.