The occasional upside of a bad movie is a performance that tattoos itself on your brain. Not far into "Alpha Dog," Nick Cassavetes's unwitting love letter to the teen gangstas of the San Fernando Valley, Ben Foster arrives high as a blimp, inked with body art. Holy Morton Downey! He's a Jewish neo-Nazi, too. He has about four scenes as the half-brother of a kidnapped kid. In the most unexpectedly funny one, he crashes a house party, socks one lady partygoer, spin-kicks another, slaps somebody else around, screams, suavely pulls himself together, and barks an announcement ("If anybody sees Johnny Truelove, tell them Jake Mazursky is looking for 'em. Thank you.") The other kids look at him in exhilarated awe. They've just watched the best Michael Jackson video in 12 years.

WESLEY MORRIS