The scene: dinner at my aunt's house about 2 years ago. My then-5-year-old cousin is sitting in front of her plate, counting in a (failed) attempt to substitute an "educational activity" for vegetable consumption. In this case, she's categorizing everyone at the table as boy or girl, and keeping tally.
I have a new haircut, and it's short. The tiny finger goes around the table, points at me. Its wielder frowns, obvious confusion growing on her face. "Girl or boy?" she finally asked. "What do you think? How would you find out?" I said, fighting the urge to laugh.
She considered this. "What do you like to do? Do you like to do things that boys don't like to do?"
"Well, let's see. I like... computers, and technology, and math, and climbing trees, and engineering, playing jazz piano, learning how to punch things... um, this may not be the best list... but lots of girls like these things too, and lots of boys like them."
"Do you like doing things that girls like to do?"
"Everything I just said is stuff that sometimes girls like to do and sometimes boys like to do."
The pause of a small child pondering experimental methods. Then:
"Do you have breasts?"
The entire table cracked up. I was wearing a zip-up polarfleece jacket that effectively obscured my body shape (which is pretty slim and androgynous in any case). My cousin looked at me for a while, considering. "Nope," she decided. (In between bouts of laughter, her mother explained that people of both genders did, in fact, have breasts, that her daddy had breasts, that some men could actually be fairly well-endowed - just look at statues of the Buddha - and so forth.)
This went on for a while. Finally, exasperated, she threw up her hands. "So, boy or girl? How do you tell?"