This is a story about two 18-year old boys, Tenoch (Diego Luna) and Julio (Gael Garcia Bernal). Both are about as immature as teenage boys come. They are obsessed with sex, sneak off with their girlfriends to do it, and have an untamed approach to sex that always leaves them satisfied too quickly and their girlfriends not satisfied at all. When the girls head off to Italy for the summer, Tenoch and Julio plan to spend their time getting drunk, getting high, and jerking off. At a party, they meet Luisa (Maribel Verdu), the wife of Julio's distant cousin. They think she is beautiful; the fact that she flirts with them only adds to her exotic allure. One of them makes up a lie about going to a beach for a week (the paradise he describes doesn't actually exist). They ask her to come along; she declines.

A road trip leads to self-discovery for two teenagers and an older woman in Y Tu Mama Tambien

Then Luisa learns that her husband has cheated on her. She calls the boys and says she wants to take them up on the offer. There is no beach, but they hop in a car anyway and start driving, determined to make up a plan as they go. Discussion soon turns to sex: what positions the boys do it in, what they've done to arouse their girlfriends, etc. Talking about sex to this older, more experienced woman is the ultimate turn-on. At a hotel later on, Luisa offers to have sex with Tenoch. He is typically wild, and she tries to teach him some maturity in his lovemaking. Julio finds out about the tryst and, in a jealous moment, makes a shocking confession to his friend. Later, Luisa tries to teach Julio some sexual maturity as well. It's not fair to give away what happens, but it changes the scope of the boys' friendship forever.

The sex talk in Y Tu Mama Tambien is enough to make the characters in American Pie blush. Like most adolescent males, Tenoch and Julio are obsessed with all things sexual. It dominates their thoughts and conversations. The film also has full frontal nudity, scenes in which characters visibly pleasure themselves (albeit from a distance), and a handful of racy sex scenes. Director Alfonso Cuaron (A Little Princess, the Gwyneth Paltrow version of Great Expectations) doesn't shy away from much.

Some will ask the inevitable question: Is this pornography? No. The sexual content is not here to titillate or arouse. (The theater where I saw the film had a sign out front warning: "If you only came to see the sex, you'll be disappointed.") Instead, the explicitness is used for authenticity. Simply stated, you can't understand the change these characters go through until you understand the immaturity of their sexual attitudes. And make no mistake: this is a movie about the characters. It's about growing up, being more responsible about sex, understanding that it is an act that has weight, meaning, and significance.

The MPAA doesn't get this. They have no reservations about slapping an R rating on a film like Van Wilder, in which frat boys gleefully drink dog semen. Or The Sweetest Thing in which a young woman gets a penis caught in her throat while performing oral sex. Those movies don't take sex seriously, so the MPAA lets them pass. Any film that takes the issue seriously and tries to present it with intelligence is a threat to the simple-minded censors who dole out ratings. Isn't this the kind of movie they should be promoting - one that offers a worthwhile message about sexuality instead of tossing up misogynistic or homophobic nonsense?

When this film was over, I found myself really thinking about what I had just seen. The performances take the already-compelling subject matter to an even deeper level. Maribel Verdu is especially effective as a woman who is driven to use her sexual power for something positive after her husband has used his to be destructive. She seems all cool and collected on the outside, but inside there's nothing but pain. Diego Luna and Gael Garcia Bernal are so right, so believable in their roles that you often feel like you're watching a documentary. They capture the quintessential spirit of horny 18-year olds everywhere. Put together in a story of friendship, betrayal, and awakening, the actors help create a picture that doesn't disappear from your mind the second you step outside.

Y Tu Mama Tambien is an excellent movie, but even more, it's a call to arms. If you want to see serious-minded, artistic movies that just happen to be for adults, then cast your vote at the box office. Send a much-needed message to the people who don't want you to see this kind of thing. You'll be supporting a great film in the process.

( 1/2 out of four)

Y Tu Mama Tambien is unrated but contains sexual content and adult themes that make it unsuitable for viewers under 18. The running time is 1 hour and 44 minutes.