“It started in the summer when I overheard two girls talking about a friend of theirs. When this friend had been on tour with the rugby team at her university, she’d drunkenly ‘done a shit in the sink.’ ‘Ew, gross,’ one of the girls said to the other. ‘She’s not a girl if she did that. She may have a vagina, but she’s not a girl.’

“I thought that was pretty funny. I wondered how many things I had done that would make me not a girl in their eyes. And what about my girlfriends? I set up a Facebook group to find out what disgusting things everyone had done. It wasn’t just nosiness. I’d realized that most of the pressure women feel to behave in a certain feminine way comes from other women. If we could admit that we are all pretty gross, then maybe the idea of what makes you a girl can change a little.

“The response to the Facebook group was amazing. Once we got going, it turned into this huge repulsive outpouring. At first I almost wished I could close the lid again. There were stories that made defecating in a sink seem like a pretty polite thing to do. But then it turned into something more. We started asking questions—‘Is it just me?!’—and offering helpful hints to each other about things like those new period pants I’ve yet to try. It turned out we really needed this outlet. I decided to illustrate the best stories and make it into a book. I hope it reaches gross girls and neat girls alike, and any boys who still think girls don’t fart.”

—Tallulah Pomeroy