around here it depends on the crowd. High school, it was always Donnie Darko, Boondock Saints, and a bunch of shitty vampire movies for the suburban "we're so oppressed even though we're privileged white kids" crowd. For the "You just hate me because I'm black, even though I'm really a privileged white kid" crowd it was almost always Sky High and Half Baked. For the "Dude, I'm like... soo... high" crowd it was Fear and Loathing in Las Vegas (although I approve of that, HST is fuckwin), Mallrats, and Jay & Silent Bob Strike Back.
For my crowd the "Pop-culture Junkies" it was usually the slightly less known tings, Fear and Loathing among them. Lord of the Rings, if only for Gollum imitations during class, Red Vs. Blue (still what I quote all-too-much), and for me and me alone, High Fidelity, because I push that movie like a drug dealer on everyone I know, as a precondition to further interaction. They don't have to like it, mind you, they just have to SEE it.