On a podcast today, I heard about a clever woman who some years ago created a book called "Everything Men Know About Women."
She self-published and got women's clothing chains to stock it as a gift item. She didn't take returns, and wouldn't take an order for less than 100 at a time.
She said whenever the buyers were women (which was most of the time), they ordered the book.
She ended up selling hundreds of thousands, then a publisher gave her a lucrative deal and she retired.