This happens to me a lot.
I’m chatting to a friend about something, probably a story about my general social awkwardness, and then somebody comes into the room and hears JUST the last part of the conversation.
It could be explained quite easily, and yet without the context of the full story, they immediately give me a funny/dirty look…before backing out of the room quietly.
The problem lies in the fact that we are natural storytellers/listeners. When we hear part of a story, we automatically want to fill in the blanks. And that’s where our own active imaginations often get away from us. (Human beings are naturally quite disgusting sometimes.)