Or, what happens to many, if not all, trans girls.
Basically, it's the experience of being treated as a boy instead of the girl you are. Repeatedly. Over and over. From birth. You're given the wrong clothes, the wrong haircut, a wrong name. And when you can't be a boy, when you behave in non-boyish ways, you're punished for it. You're ostracised (if you're lucky, it ends here), bullied, beaten. You get bruises for not behaving like a boy. No-one wants to be your friend because you're considered too weird, too odd, too fucked-up.
You can't be the girl you are, either. Crossing over is not allowed, and if you're brave (or foolish, take your pick) enough to try, you will be told in plain terms that you're a weirdo, a freak, and not able to anyway so just go back to trying to be a boy, m'kay?
That's the reality of forced masculinisation. That's the reality of good many trans girlhoods, including mine.