I know, it's kind of an odd topic, but I got lost in one this morning.
Really truly. I know it sounds a little bit silly, but perhaps you've never encountered this particular restroom. While it doesn't have the all-too-common two mirrored rooms of stalls, it is quite large, and confusing, and has an extra door where the exit should be but isn't. I think it might be a closet. In any case, I looked rather silly when I tried to open it.
Exiting the bathroom wasn't the only difficulty, of course: On entering, I found myself in what looked like someone's very nice living room, minus windows. It even had a couch and a couple of comfy chairs. (I think this is the real reason you see women going to the bathroom in herds--so they can sit and socialize and not have to deal with all the annoying men. Just a thought, though.) For a couple of minutes I wasn't sure I was in the right place--it took me a while to find the door to the real bathroom from the first room, and even then the stalls were neatly hidden away in a corner.
All in all, a nice, pleasant design, if a little bit frustrating for anyone in a hurry.
This webcomic sums things up quite nicely, I think: