Mel Brooks is sometimes like an inside joke. You get it or you don't. Of course, sometimes you get it more than other times. The guy who roared in my left ear at the screening of Brooks' sixth film, "High Anxiety," got it. But he sounded like either a laugh-for-hire or a mad laugher - that is, someone who turns up jollity beneath every rock. A number of presumably serious-minded people scowled at him, but he kept right on laughing.

What is it with Mel Brooks, anyway?

Chaplin suffered all the cruelties a big bad world could ever inflict on the little guy,Laurel and Hardy used routines of the dumbo bouncing Falstaffian antics off the straight man, and so forth.

That Brooks has studied the forerunners of comic technique and borrows heavily from the best is obvious in his films. But whether he tickles your ha-ha frequently depends on how well he weaves his philosophical potshots into his comic routines and how familiar you are with the genre he has chosen parody - Western in "Blazzing Saddles" horror in "Young Frankenstein," silent movies in "Silent Movie."

This time, in "High Anxiety" Brooks has chose to lampoon, with affection, the style of Alfred Hitchcock and the genre of suspense. Co-written with Ron Clark, Rudy Deluca and Barry Levinson (who also play in the comedy with the director), "High Anxiety" is very main-street Mel Brooks. Though neither as original as "The Producers," his best film, nor as funny as "Young Frankenstein," High Anxiety" remains adequate zany. It's likely that Brooks fans will find something to laugh at, although probably not as much as the mad laugher.

As usual, Brooks effectively uses music (by composer John Morris) as cornstarch - to hold together and counterpoint the mix of comedy and suspense.

The plot begins to thicken almost immediately, as the smell of foul play emanates from the Psycho-Neurotic Institute for the Very, very Nervous, a California asylum. Its last two directors (heh-heh) perished in a most mysterious manner, the new boss, Richard H. Thorndyke (Brooks), learns from his driver (Ron Carey). A Nobel Prize-winning psychiatrist who suffers from a severe case of high anxiety, Thorndyke is greeted by a plotting staff of kinky comic bizarros: Cloris Leachman as Head Nurse Diesel, Harvey Korman as Dr. Charles Montague, Dick Van Patten as Dr. Wentworth. One Professor Lillolman (Howard Morris), who once tended Thorndyke as former shrink (for high anxiety) mentor, is also in residence.

Suffice it to say the cast makes for an on key comic chorus, especially Madelin Kahn as prissy Victoria Brisbane, the daughter of millionaire industrialist (and unwilling patient) Arthur Brisbane. One especially amusing sequence has Victoria hilariously dropping her veil of Victorian manners to respond to what she thinks is an obscene phone call. And Leachman renders a delighfully hostile Nurse Diesel - Brooks' caricature of the Nurse Ratchet archetype - who proceeds to make life difficult for everyone except Montague. Oh, how he pines for the nocturnal bondage of her whips and chains!

Brooks quietly laces his mock thriller with slightly piquant put-downs of psychiatry, sexual kink, greedy power-grubbing and so forth, but the satire doesn't sting as much as in "blazing Saddles."

Visual allusions to scenes from Hitchcock ("The Birds, "Vertigo" and "Psycho") fail to work as well as intended because they're so obvious - and you can't help wondering if they'd work at all with audiences who hadn't seen those films.

"High Anxiety" has the comic nourishment of popcorn: It's fun enough to eat, but somehow not as satisfying as a good dinner. Even if you understand what Brooks is trying to pull off, that doesn't mean he always does it.