I got caught in the ladies' room at work once. I thought the lady was gonna freak out on me and label me as some sort of a sex offender. The fact that there's a sofa, but no urinal should have been a dead giveaway, but instead, I was just confused, figured the guys in this building were just weird girly men, and went into a stall to take a dump.
Right after I sat down, I heard someone walk in. It sounded like the person who'd just come in was wearing shoes with hard surfaces.
Like the high heels.
Then I realized why there's no urinal in this bathroom, and why there's a fvcking sofa! I was about to take a dump in a women's bathroom, and there was a female worker standing right outside.
Fortunately I hadn't "started", so I just stepped out of the stall, and the lady looked at me funny(as a side note, she was rather hot), and I explained that I thought I was in the men's bathroom. Not smooth. She tried to make me feel better by saying that she makes the same mistake all the time. I left the room quickly. I felt like a dumbass.
In my defense, my office was in another building, and this was outside of my usual routine. I don't work there any more, but that's because I took another job for more money.