I'd have thought it'd be hard to top the Secret Service close-call affair the same day, but I did.
When at Reagan National Airport, about to board my flight back home, I went to the bathroom.
I rushed into the bathroom. I walked past the stalls looking for the urinals, but then there were more stalls. A lot of them. Something was wrong. Where where the urinals?
Then I realized I, a man, had about 6 women around me, staring at me in amazement with wide open eyes. I realized I was in the women's bathroom! I was way into the bathroom, having passed several people I hadn't paid attention to as I looked for urinals!
Luckily, everybody laughed. I was so embarrassed, and apologetic as I exited the bathroom... (while more women were walking in...)
Bonus: after I urinated in the men's bathroom and got back to my gate, I realized I didn't have my water bottle, so I had to run back to get it. It was hiding camouflaged.