I once found myself in the wrong restroom while dressed in a mouse costume...
I played 'mouse' in a production of Alice in Wonderland one summer, and we were promoting it at the local park - in full costume. I was already in a stall in the park restroom when a man and his son came in. Realizing I was in the men's room, I tried to wait for them to leave... but they stayed by the sinks, and I knew everyone was waiting on me outside... so I took a run for the door.
Awkward for me, scary for the child, I'm sure.