I used to teach. My students would ask me, "What are you going to be for Halloween?" and I'd answer "I'm going to be absent."
They'd ask again, "No, what are you going to be?" I'd insist, telling them I was going out of town and cover the substitute rules.
The next day I'd show up with my hair cut short (it is normally long), my beard shaved off, wearing glasses (normally wear contacts) and in a suit and tie (normally in a t-shirt). I'd speak with an Indian accent. It was always good for a double take. One of the maintenance guys called security on me once.