Once many, many years ago (I was a crossdresser then too...), I was travelling on business in drab. It was summertime. I was at the airport, had just checked in, and went to use the toilet before clearing security. I had to use a stall. So I went into what I thought was the men's room, sat down in the stall and went about my business. I hear someone enter the next stall, and next thing you know I see a pair of female sandals and very red painted toenails in the next stall. Oh crap I thought, I must have been absent-minded and entered the wrong restroom. So after I was done, I sat there contemplating how to discreetly make my escape, gauging the route between stall and exit through the crack in the stall door. I waited for what seemed like a lull in the traffic, opened the stall door, and started to bolt to the exit when I noticed... the urinals!
I still don't know if the person in the next stall was a sister, or a GG who mistakenly used the wrong restroom. But I had a good laugh over it afterwards.