While Marji is in the basement, she commits the self-destructive action of smoking a cigarette in order to “kiss childhood goodbye” and assert that she’s “a grownup”.
Marji is the protagonist in the book Persepolis by Marjane Satrapi. The story is about a young girl growing up in Iran during the Islamic Revolution. In the given passage, Marji is in the basement with some friends and decides to smoke a cigarette, which she views as a symbol of adulthood. She believes that by smoking, she is asserting her independence and showing that she is not a child anymore. However, smoking is a self-destructive behavior that can cause serious health problems and is not a responsible way to assert one's adulthood.