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** 1/2 “Three O’Clock High.” MCA. $79.95. PG-13.

Teen comedies have become such a disreputable genre that, for part of the time, this 1987 nightmare comedy is a pleasant surprise. It’s a cracked, clock-race thriller about a hapless student (Casey Siemaszko, in a Richard Dreyfuss mood), facing after-school extinction at the hands of a psychopathic transfer. And it’s done in an amusingly self-conscious, heightened style that suggests young director Phil Joanou is trying for “The Road Warrior” of teen comedy: intense angles, elaborate tracking shots, excruciatingly stylized acting. Overall, it’s too coercive, and the sadistic gung-ho climax is a real mistake. But Joanou occasionally revives our delight in the sheer mechanics of film making.