Y Tu Mamá También

A 2001 movie by Mexican director Alfonso Cuaron (of Children of Men and Harry Potter and the Prisoner of Azkaban fame). The title means, (more or less), "And yo momma too." Two boys go on a trip to find a beach called Heaven's Mouth. Yeah, it's a wild goose chase, but they're really going to have sex with a beautiful woman.

Tropes used in Y Tu Mamá También include:

A Threesome Is Manly
Circumcision Angst: Subverted, Julio calls Tenoch a faggot and tells him to blow up the balloon.
Downer Ending: Luisa dies of a brain tumor, Tenoch and Julio never speak to each other again.
Everybody Has Lots of Sex: Before the events of the movie, Julio and Tenoch screw their girlfriends like crazy. Then it's revealed later on that they've been screwing each other's girlfriends like crazy. And then once they go on their trip with Luisa they screw her like crazy. It isn't until they try to screw each other like crazy that things go bad...
Fan Service: The girls get naked. A lot.
Gag Penis: "I may be a faggot, but at least I don't have an ugly dick."
The Grunting Orgasm: Both boys when they're jerking off into the pool.
Heterosexual Life Partners: Tenoch and Julio. Maybe.
Ho Yay: Kind of the point. The fact that the boys regularly get naked and masturbate together is just Foreshadowing.
Hypocrites: When Luisa brings up the possibility of the boys' girlfriends cheating on them, they get quite defensive despite the fact that the whole trip is to have sex with Luisa. But when they find out that they screwed each others girlfriends... Whew boy!
I Banged Your Mom: The trope is right in the title.
If It's You It's Okay: Subverted. Their friendship is fine until they have a threesome.
Kissing Cousins: Albeit cousins by marriage.
Mangst
"The Reason You Suck" Speech: Luisa gives one to Tenoch and Julio, calling them on their bullshit and Foreshadowing that that they really want to screw each other.
Shout-Out: Charolastra means, roughly, "space cowboy." Also one to Thundercats.
Spiritual Successor: To Por la Libre.
Stacy's Mom: Luisa.
Two-Person Pool Party
What Do You Mean It's Not Political?: The movie took place just after many, many cases of showing social injustice in Mexico. Chuy is the most heartbreaking. Oh, and Tenoch has an Aztec name (indicating nationalism) but is circumcised (indicating Americanization).
Your Cheating Hearts