FAST TIMES A T RIDGEMONT HIGH "There's only two things 1 want out of life," says the glassy-eyed hero of this movie to his exasperated English teacher: "Some tasty waves, and a righteous buzz." It's a line representative of what's finest and funniest about this film. For here is a portrait of modern high school life that speaks lightly but truly to the fears and trials of post-Watergate teens. While neither as slapstick (in the visual, Mack Sennett sense) as Animal House, nor as apocalyptic and biting as Over The Edge, Fast Times At Ridgemont High is both funny enough and serious enough to hold its own in their company. Cameron Crowe's screenplay (based on his bestselling book) captures the language of its characters as hilariously as Frank Zappa's song, "Valley Girls," does his. Director Amy Heckerling wisely emphasizes character and relationships over bellylaughs, but keeps the laughs coming nonetheless. The film's main strength issues from two performances: Jennifer Jason Lee's, as the 15-year-old heroine surviving her first (disastrous) sexual experiences; and Sean Penn's as the serene doper-surfer quoted above, surviving little more than his last righteous buzz. Lee is at once so naturally girlish and womanly, so timid and yet matter-of-fact, that she becomes an archetype of earthy teenage femininity. Sean Penn is something else again a skinny John Belushi, a gifted actor creating the archetypal party animal, as comic as Lee's character is serious. Like Belushi, his character isn't a role model (no matter what Daryl Gates might say), but a figure of wish-fulfillment, a creature of pure libido, like Mr. Toad in The Wind In The Willows a figure who, if anything, purges an audience's wishes through laughter, in the act of expressing them. (FXF)