I arrived at an airport, and had just picked up my luggage. I suddenly really needed to use the bathroom, but I couldn’t find one. I started taking a down escalator, but then saw a bathroom on the level I was leaving. I started sprinting back up. Near the top, the escalator stairs change their height and I tripped, getting what looked like a bloody snakebite in my knee from the jagged step edge. I rode down and found a different bathroom.