In the The Standard Edition of the Complete Psychological Works of Sigmund Freud (1923) the father of psychoanalysis enters the term Verleugnung as part of his article "The Infantile Genital Organization". According to Freud, Verleugnung was a reaction caused by a form of psychological emasculation, or "castration" mainly represented by
a specific mode of defense which consists in the subject's refusing to recognize the reality of a traumatic perception.
According to Freud, the young male suffers a form of shock, frustration and even disappointment when in the presence of a young female, particularly when the differences in genitalia are made aware. As a result, males tend to overlook the differences and pretend that everything is the same; that, supposedly, the natural tendency of "man" is to be oblivious to the obvious and pretend that things are the way that they imagine them to be.
In more colloquial terms, we could conclude that Freud really wants to tell us that males are unable to accept shock, especially in circumstances where they feel completely lacking control. Situations like these may include death, divorce, lying/cheating, being left destitute, and other things over which most of the time we have some say or hold on. However, when something surprisingly shocking occurs, men prefer to shrug it off and move on, under the premise that things will take care of themselves.
Freud also dubs disavowal as "the splitting of the ego". This is because, theoretically speaking, one can only ignore reality to a certain extent (assuming that we have not become psychotic and lose our grip on it). Hence, a normal brain can only ignore, hide, and pretend not to care "so much". The fact that the male does it anyways does not indicate that he has indeed disavowed reality completely. Instead, it means that the male has made a temporary break up with himself, his reality, and his present condition for the sake of tolerating the immediate shock. However, it is clear in the man's subconscious level that there is INDEED a situation that needs taken care of: that is precisely why the opposite action is taken and the facts are ignored and shrugged off instead.