The first sexual intercourse of the adolescent is a specific moment when his being-in-the world changes (i.e. His relationship to the world),stamping its traces within both his body and psyche. Being utterly constituent of his future as an adult, it does not however makes him totally an adult as such. With référence to the load of excitement it carries with it, one may consider it as both some kind of necessary and building trauma in the evolution of the subject, hereby violently confronted to the fundamental question of his desire and enjoyment.Supporting myself on some specific reading and understanding of freud’s approach of trauma, repetition and the death instinct, i will suggest that one might view such a « trauma » of the first intercourse at adolescence as some kind of « perspective object » for the psyche, enacting some « anticipatory repetition » : the latter enabling to thwart the destructuring aspects of such a trauma for the psyche, e.g. Softening its load of excitement by « partly » elaborating – through the repetition(s) included in such an act – the traumatic effect of the unexpected surge of the other in oneself, i.e. The very other revealing itself in the acute moment of excitement with which the adolescent will have to deal with in order to become an adult. Such a question will be illustrated with the case of an adolescent whose obsessional symptoms and their symptomatic unfolding in psychotherapy may be retrospectively understood as caught within that very « anticipatory repetition ».