It certainly won't help to embarrass him, and cry and storm about pornography. That doesn't mean avoiding the important questions. It was God who decided that by their early teens boys (and girls) should get hit by powerful sexual feelings. For some boys a nudie magazine is an opportunity to satisfy curiosity about the anatomy of the opposite sex. For others there is pleasure in the beauty of the female body. God designed a woman's body to be very attractive. Many men have a fascination with women's breasts. But appreciation of beauty is very different from using hard core pornography to think about raping a woman.
If your son sees you are horrified at any mention of sexual feelings, he will clam up. He will make sure a large area of his life is never open to you again. This is why many mothers lose communication with their son in their teens. Harsh judgments, cruel condemnation, and humiliating embarrassment are always fatal. How then can you convey the important values for genuine love and a happy marriage? The art is to keep the conversation open with your son. Rather than stony silence, pick up the questions of sex or nudity, rape or abuse that arise constantly in the news, on television, or in a movie you saw. Rather than avoid the topic, try to express your own opinion without embarrassment. For example you might say : The hard thing about being a teenager is being hit by all sorts of sexual feelings.
Love is caring about the freedom of the other. A man who really loves a woman will never force her. That is why rape is so awful. Many of the great artists have loved to paint the female body. There is a big difference between the artistic appreciation of beauty, and treating women as sex objects. Magazines are pornographic when women are pictured as sex objects to be abused. In Playboy magazine some of the women are photographed very tastefully.
Let your son see that you are not embarrassed by these questions, and are prepared to express the distinctions that are important to you. He may not say anything immediately, but slowly he will gain confidence that you are not horrified by his male sexual feelings. If you do find your son reading Playboy magazine, rather than hit the roof and go into a tantrum, you could surprise him. "Let me see which of these girls I would l like you to marry. Now she looks very sweet. I don't think I would want that one as a daughter in law." That would make clear that you are not a prude, and it leaves the door open for later heart to heart conversations about genuine love and marriage. A boy needs that from his mother.
Many Christians are worried about Jesus' words : "You have heard that
it was said, 'You shall not commit adultery.' But I say to you that everyone
who looks at a woman with lust has already commited adultery with her in
his heart." This text is not about finding women attractive. God has designed
us to enjoy the beauty of the opposite sex. See the commentary on
5:27-28. And for a fuller discussion see Adultery:
An Exploration of Love and Marriage.