This happened while I was passing out candy on Halloween.
Let me start out by saying that my Halloween decorations include a talking skeleton who sticks out his tongue and has eyes that bug out. It's activated by motion. I hang the skeleton on my door, and it gives me a heads up when the trick or treaters are entering my yard.
Three kids who live down the street from my house (I don't know where they live exactly, but I see them riding their bikes past my house all the time) came to my door trick or treating. I believe they are first or second generation immigrants to the U.S., but had never talked to them before. They weren't wearing costumes that I could tell (it's cold in my area of the U.S., so they could have been wearing costumes underneath their coats) and I gave them some candy. About five minutes later I opened the door to find they had returned with their elderly grandmother. I don't think she spoke much, if any, English. She was laughing away at the skeleton on my door, and I figured they had come back to show her the skeleton. I stood there with the door open for a minute waiting for them to leave again, when one of the kids piped up and said she wanted some candy too.
I thought that they didn't understand the trick or treating customs, and I didn't feel it was my place to let them know that the candy was just for the kids, so I gave her a piece, and they left afterwards. To be honest, I also felt that since they were neighbors I wanted to keep on their good side.
I'm curious, would you have corrected their misunderstanding about the custom? I know if these people were friends or acquaintances I probably would have, but with strangers I wouldn't feel comfortable doing so.