Y Tu Mamá También has been casually referred to as a Spanish-language American Pie, perhaps because both films include footage of taboo body fluids floating in liquids they don't usually call home -- a swimming pool here, a beer there. But that comparison doesn't nearly do justice to Alfonso Cuarón's bold, sexually explicit yet artistically justified coming-of-age piece, which climbs outside the box at every turn. More generous films to associate it with are Run Lola Run and Amélie; both share Mamá's curiosity about the interrelationship of seemingly unlike people and places, and contemplate the pasts and futures of bit players in a manner that seems essential, not superfluous. Yet it's not as glossy as those films, either. Mamá retains a documentary-style realism that's less dependant on set pieces, preferring the messy yet basically benign continuum of life. Mamá's illuminating narration is never intrusive, even though it cuts off the soundtrack in a way that sounds like abrupt speaker failure; it contextualizes the action while leaving the deeper profundities to the viewer's own thoughts. Cuarón's fascinating decisions are as regular as the free-flowing bull sessions so naturally performed by lead actors Diego Luna and Gael García Bernal in and around Mexico City, and on their road trip to self-discovery. Cuarón, seeming more comfortable in his element than in a Hollywood release like the Gwyneth Paltrow vehicle Great Expectations, challenges the actors' talents in a handful of takes that last minutes on end, many of which include the camera moving seamlessly through the environment. Even with all these accomplishments, it's still as funny and as titillating as anything out there -- maybe because it doesn't have to try so hard to do either.