I don't reeeeaaally have any stories that fit in this thread, as when I was a kid I felt less like I was born in the wrong body, and more that people were exaggerating the differences between boys and girls and should just get over it. Which tbh I still think, but I also think I'm trans, so.
Most of the stories I do have are more frustrating than funny, as well. I remember my mother talking about tomboys, and since I'd always known I got on better with boys, preferred my male friends, and thought more like a boy (though I wasn't able to put this latter one into words then, but I knew it all the same), I told her I was a tomboy. She replied quite rudely that I wasn't, and she made it sound like I'd just said something really awful that I was totally stupid for saying and should feel ashamed for.
She also said that all tomboys liked sports, and that I could never be a tomboy because the only sports I liked were running races and because I liked drawing and reading... and those were exclusively girl's activities apparently. All the other boyish things I was into were completely invalidated by the fact that I drew. Meanwhile one of my friends was a boy who also drew a lot, and that didn't mean he wasn't a boy. I was so, so pissed off. Still kind of am, really...