This paper argues that sex education must move beyond a focus on compliance so that we may risk the uncertain work of thinking. How might we understand the work of thinking in sex education if we begin from the assumptions that learning is conflicted, that sexuality resists being educated even as it inspires curiosity, and that the subject of sex education is herself divided and liable to act in her own worst interest? Drawing on theories of thinking in psychoanalysis, I consider this question through the status of prohibition in sex education and argue that prohibitions can function either as a way of shutting thinking down or as a tentative step towards thinking an intolerable thought. The documentary film "Desire" illustrates the potentially productive use of prohibitions and suggests some of the conditions necessary for developing the capacity for thoughtfulness in sex education. (Contains 4 notes.)