An Abundance of Katherines by John Green

Colin, a former child prodigy, has dated nineteen girls named Katherine and they have all dumped him. In an effort to forget his sorrow he embarks on a cross-country road trip with his friend Hassan. Colin and Hassan's adventures include the Arch Duke Ferdinand, the creation of a a mathematical formula for predicting who will get dumped in a relationship, and a company that makes tampon strings. It all makes sense in the story; believe me, and getting everything resolved is a hoot. This book will make you smile.