What begins as assigned diary entries à la Sei Shonagun’s late-tenth-century The Pillow Book turns into Lotus Lowenstein’s tart, irreverent take on sophomore year, written in “franglais.” The young Brooklynite is determined to become an existentialist, visit France, fall in love while there (preferably with someone like Jean-Paul Sartre, “the père of existentialism”) yet still retain a life of freedom (like Simone de Beauvoir) and shed a few kilos for a more French Women Don’t Get Fat figure. But when the only male French Club member shows an interest in both Lotus and her best friend, Joni, Lotus must determine if her existential quest is worth losing her friendship and independence. While some humor may be funnier to adults more familiar with French culture than the average American teen, readers of any age will savor Lotus’s panache; her French tricks to transform Ms. G., her mousy English teacher, and the French Club’s expedition to find some of Canada’s best poutine (French fries topped with cheese curds and covered with brown gravy). Chick lit par excellence. (Fiction. 13 & up)