In The Stranger, Camus gives us an absurd hero in Meursault who loves life, hates death, and scorns the gods. He also loves swimming, sex, sleeping, eating, smoking, and going to the movies--all life affirming activities. As such, Camus would rather his hero laugh at a movie rather than cry at a funeral. Movies celebrate life; funerals celebrate only death.
Merusault's mother dies Wednesday or Thursday. The vigil is Friday, and Meursault meets Marie Saturday for a swim, movies, and sex (she spends the night). Together, they see a comedy starring Fernandel, a French actor. Marie notices Meursault's black tie, and she realizes that he is supposed to be in "mourning." She thinks it's a bit odd that he would want to swim, go to a comedy, and have sex so soon after his mother's death. Later, in Chapter 4, Meursault and Emmanuel go to see two movies together during the work week nights.
Movies are places where people come together to view something as part of a cultural ritual. Movies are not Camus' targets. Movies are used to juxtapose the other ritualistic places where people gather to celebrate death: funerals, vigils, churches, courtrooms, and public executions (all of the people in these places will judge and condemn Meursault later). Movies are harmless compared to these institutions. These places are the "gods" that Camus says his absurd heroes should scorn.
Camus is using the act of going to a film to show that Meursault is not affected by his mother's death. He can go to a funeral one day and then see a comedy the next. He does not reject casual relationships the week after the funeral. Is that so wrong? Camus thinks not.
To laugh when one should cry may look like a contradiction of emotions, and it may look like Meursault is a cold, apathetic person. Meursault rejects social expectations that limit a person's freedom and love of life. Society expects him to wear black, look sad, and refuse entertainment and casual dates. In effect, society expects Meursault to act like he is dying.
Camus rejects this culture of death. Why can't he go to the movies and see comedy? Why can't he go swimming? Why can't he have sex that night? Who makes these silly cultural rules about the mourning process?
At the end of the novel, Merusault, just before he is to be executed, will say that no one has a right to cry over his mother's death. Merusault loves life: the water, the sun, girls in bathing suits, funny movies, sleeping, eating, drinking. All these acts are celebrations of life. Wearing a black tie and locking oneself in an apartment all week only celebrates the culture of death that Camus' absurdism wants us to escape.