I once dressed for an interview, and on the way back popped into a comic book store. Inside, a guy started asking me about my little pony stuff - he thought I was the manager..
I was once going to an event in a full suit, but before that, I attended a guest lecture on my university. I was just a regular attendee, but my clothes were enough for people to think I manage this guest lecture. I was handed the keys to the lecture hall, and people would come to me with questions and issues...