I've used the ladies room several times without knowing it. I have a very high IQ. Yet, I seem to miss things like the little woman sign on the door and other small details like that. Guess I'm always too busy thinking about developing power (tony robbins addict), physics or business ideas to notice little things like signs on doors, women at the sink, etc. Anyway, I generally figure it out when I don't see any urinals and I'm like "WTF! Where are the urinals" then I play it off like I'm not shocked out of my head and hit the stall. I generally get only a minor comment and lots of strange looks.