So a few months ago I read Stiff: The Curious History of Human Cadavers , by the smart, funny, and irreverent Mary Roach. I loved it. Today, on my way home from dropping plumtreeblossom off at her house, I overheard on NPR that Mary Roach had a new book out about the science of sex. It’s called Bonk . You can bet I placed an order as soon as I got home.