On the train to New York, a woman sits next to him. She notices his Pencey bag, and says her son is Ernest Morrow. Holden hates Ernest, but lies and says that Ernest is extremely popular and would be class president if he would just let himself be nominated.
Holden hates phoniness in others, but can't avoid it in himself. By lying to people, he makes himself feel superior. This gives him an excuse for his loneliness: he's too smart for them.
Holden introduces himself to the woman as Rudolf Schmidt, the name of Pencey's janitor, and invites Mrs. Morrow to have a cocktail with him in the club car. She asks why he's out of school. He says he's leaving Pencey early to have surgery for a brain tumor.
Holden may hate adulthood, but when he deals with women he often tries to act older then he is. Perhaps he hates adulthood because he feels he can't be a successful adult.