Cycler is a young adult novel-released today-by Lauren McLoughlin that plays with themes of sex, menstruation and gender-bending. The story concerns a girl named Jill who is living with a secret: Every 28 days she turns into a horny, teenage boy named Jack for 4 days, then snaps back to normal, and the cycle begins again. We haven't read it yet, but the description here makes it sound so great and smart, that we'll probably pick it up for a Labor Day beach read. [Boing Boing]