When I was 9 or so, I was on the schoolbus with a female friend when an older boy came and sat next to us. "You're not really girls," he said. "You look like boys to me. You look just like boys." He wasn't joking around. He was accusatory.
"We're girls!" we said, confused and slightly hurt.
"Oh yeah?" he said. "Prove it. You know how." He glanced at our crotches.
We went back and forth a few times with "But you know we're girls!" and "Nope. Only one way to prove it." My friend, embarrassed and flustered, flashed him her labia. I didn't, but I also didn't stop her or tell anyone. He went away.
It scares me how much of people's adult lives are spent reenacting this same scene. Simply identifying myself as a woman doesn't ever seem to make me woman enough. If I don't look woman and act woman and talk woman, I might accidentally be a man, and that would be terrible.
This is what the intellectual-feminism types call "performing gender." It's when you put on makeup not because you like to wear makeup, not even because you think the makeup makes you look attractive, but because you don't want to look like a man.
And at its heart, it's subject to a horrible circularity of argument. If a woman has visible facial hair, saying "she doesn't look like a woman" ought to be a blatant oxymoron--you're looking at a woman right now, so I'd say that's what a woman looks like! For a woman to change her appearance for the sole purpose of looking "more like a woman" ought to be as silly as dressing your dog up as a dog.
This is an equal-opportunity form of sexism, too--how many times a day are men implored to act like "real men"? With the implication being that if they screw it up, they'll be... fake men? Women? Gay? Probably gay. From how they dress to how they walk, the desire to not be gay dictates way too much of the social behaviors of millions of guys who weren't even attracted to men in the first place.
(Digression: I think this constant pressure to broadcast "I'M A STRAIGHT MAN REALLY I AM" is responsible for, among many other things, street harassment. Most guys who hoot at women in the street aren't doing it because they think it'll make the woman drop to her knees in adoration and arousal; they're doing it to prove to their buddies--or themselves--that they're a straight manly man.)
Never mind "this is what a feminist looks like"--now I want a t-shirt that says "this is what a woman looks like."