Yes - I remember doing that when I was at college. One of my friends called out my name, I turned around thinking I was going into the women's bathrooms, and then I walked into a whole bunch of men doing their thing. Of course confusion set in, and then I realized that I had made the mistake! LOL
Yes. When I was in Japan a friend covered up the part of the sign with the male and female sillouettes and sent me into the wrong one knowing I couldn't read the kanji. I figured out my mistake pretty quickly! I've also used the mens' on purpose when the ladies was occupied (in a place where it was just one cubicle, no urinals).
when I was at the Octoberfest in Brussels years ago, they had male, female and unisex toilets. I wasn't prepared to share and was a bit of an eye opener. I guess if you couldn't read the signs it didn't really matter.