At my college there are a lot of international students. There was one time when a girl was pouring water from a pitcher into her water bottle. I told her about a water fountain in another building that could do it for her.
She thanked me and her friend meets her. Her friend saw me talking to her and asks who I am in Korean.
The girl responds in Korean saying something like, "I dont know, he said something about water. He's weird."
I walk over again and say, "저기요. 제가 한국어를 말할 수 있어요."
They just smiled and were like, "Oh... really?" then walked away.
it was funny.