All the time in highschool. It started out as a joke aong my friends, since out of the twelve of them, only one was a girl and as my interests went, I was pretty Tom boyish. Then the school introduced cheapy blazers as mandatory uniform which gave me square shoulders. The head teacher honestly thought I was a feminine looking Guy for 3 years. He even asked me, without a trace of irony, to try out for the school football/soccer team, "like the rest of the lads".
On the one hand, I do have a unisex name and my haircut was androgynous at best. On other, I'm pretty well endowed for a lady.
Bah.