As the title character of The Cable Guy, Jim Carrey thrusts out his jaw and speaks in a sulky, nagging lisp, as if he were Jay Leno's infantile brother. Has any other performer derived this much joy from acting this undignified? Carrey plays a pathological leech, a cable-TV serviceman who latches onto a yuppie customer (Matthew Broderick) and convinces himself that the poor sap is his new best buddy. Calling himself Chip Douglas (from My Three Sons, one of the shows that haunt his TV-addled brain), he invades Broderick's home and office, leaving endless messages on his answering machine, crashing and I mean crashing his amateur basketball game, bombarding him with pop-psych homilies on how to win back his girlfriend, and, in general, turning his pursuit of ''friendship'' into a thinly disguised act of sadistic terrorism.
Some of this is amusing, if overly familiar, in the renegade-nuisance style of comedies like What About Bob? and Neighbors. Then comes a scene that may shock you into laughter (or out of it). The cable guy follows Broderick's girlfriend (Leslie Mann) to a restaurant and, posing as a restroom attendant, proceeds to kick the living hell out of her unctuous date, smashing him onto the floor and sticking a live blow dryer in his mouth. For a few moments, Carrey blurs the line between comic dementia and real dementia. He's funny and scary at the same time; his demons have come out to play.
Usually, we're on Jim Carrey's side, grooving on his mind warps, cracking up at his cracked-mirror happy face. But in The Cable Guy, our sympathies are divided between Broderick, the nice-guy hero, and Carrey, the deranged sociopathic imp. The star has never played this single-minded a pest before, and that may be one reason The Cable Guy lacks the exhilaration of his best work. Reined in by the character's evil lisp, his stunted camp hostility, Carrey can't fling his imagination a thousand ways as he did in the second Ace Ventura movie (or, more recently, on Saturday Night Live). The director, Ben Stiller, works with craftsmanly precision, but too much control can dampen madness. When Carrey grabs the microphone of a karaoke machine and launches into a nerdy-ecstatic rendition of Jefferson Airplane's ''Somebody to Love,'' part of the release is that the scene serves no real purpose. You feel that he couldn't hold himself back; he had to sing that song (and sing it that magnificently badly). The Cable Guy needed more highs like that one. The movie flirts with a darker Carrey, but, ironically, most of it gives us a safer Carrey, an anarchist caught in routines too patterned to let him break loose. B-