Courtesy of Kenneth Play Kenneth Play says he once injured himself from "aggressively fingering too many people," but that's the kind of mishap that comes with the territory of being an international sex educator famous—among other things—for his expertise on female ejaculation. Play is a so-called "sex hacker," which means he's done a lot of experimentation and figured out the easiest ways for people to achieve sexual goals they once deemed out of reach. (See: his excellent advice in our guide to having multiple orgasms.) "It's like being a card counter in Vegas," Play says. "You beat the odds and have an unfair advantage."