Can a comedy be so bad that it's funny? There were moments in Barry Levinson's Envy when I caught myself laughing out loud -- not at the god-awful jokes about a magic spray called Vapoorize that wondrously zaps away dog doo, or the pesky job of getting rid of a dead horse. No, I giggled, with a level of disbelief verging on awe, at the notion that people actually woke up each morning to shoot this movie thinking that they were engaged in an act of entertainment (or sanity). Jack Black, flashing a grin of dazzling obtuseness, is Nick, who invents Vapoorize, and Ben Stiller, looking like a depressed version of ''Saturday Night Live'''s Seth Meyers, is Tim, who watches his best buddy get rich off the invention and, in a moment of drunken passive aggression, shoots an arrow into Nick's beloved white stallion. As the drifter who hooks up with Tim the schlemiel, Christopher Walken seems to be mining previously unexplored levels of Method dementia (even for him), not to mention making up most of his lines.
If this were Levinson's first colossal comedy dud, I'd be tempted to give him a critical spanking and wish him well in the future. But after ''Toys'' and ''Jimmy Hollywood'' and ''An Everlasting Piece'' and ''Bandits,'' you sense a pattern: Is the once-great director of ''Diner'' and ''Rain Man'' slowly falling apart in a Hollywood he no longer fits into? A mansion with a bowling alley, silky clothes of unspeakable gaudiness -- the trappings of Nick's transformation into a wealthy happy dude suggest nothing so much as a satire of Tinseltown excess; ditto for Tim's jealousy. Envy, after all, is the lifeblood of the movie industry. But ''Envy'' leaves you with the dismaying sensation that Levinson, who should probably be off making his own version of ''The Player,'' has instead crafted a comedy of self-loathing, burying himself in a movie that deserves to be Vapoorized.