Grade: C-

One could make a strong argument that the most pernicious trend in today’s comic movies is the use–or more properly, overuse–of the fat suit. The result has been consistently less than triumphant. From Austin Powers’ Fat Bastard to Martin Short’s Jiminy Glick, from “Shallow Hal” to “Just Friends,” the device–crutch, really–has given rise to more groans than laughs, and sometimes even revulsion. Now Martin Lawrence, who resorted to the gimmick in a really big way, so to speak, in “Big Momma’s House” (2000–four years after Eddie Murphy, in whose footsteps he often follows, donned one in “The Nutty Professor”), returns to it in this sequel. He once again plays FBI agent Malcolm Turner, this time going undercover as the obese Big Momma to infiltrate the home of Tom Fuller (Mark Moses), a computer designer who’s suspected of having crafted a worm that would enable bad guys to hack into government files. Turner does so by posing as a nanny for Fuller’s three kids. What follows is a succession of vaudeville sketches that allow Lawrence ample scope for his usual mugging. Of course his presence ultimately resolves the computer-related MacGuffin, and, needless to say, has a beneficial effect on the dysfunctional Fuller clan, too.

The makeup is fine, if rather grotesque, in “Big Momma’s House 2.” What’s lacking in the movie is any real sense of style, wit or even coherence. Though generally inoffensive, the picture just sets up its unimaginative premise and then coasts along through a chain of forced, mostly unfunny episodes to a thoroughly predictable conclusion, relying on one’s tolerance of Lawrence’s supposedly engaging personality to go the distance. But one’s patience with the movie is likely to run out long before the celluloid in the projector does. As it ambles through the set-pieces–Big Momma’s visit to a spa, a contretemps at a Bingo parlor, her involvement with a high-school cheerleading contest, her eye-popping visit to a beach (complete with chase), a jet-ski interlude, and of course a big comedy-action finale–a sense of deja vu sets in. Maybe something genuinely amusing could be contrived for this character, but scripter Don Rhymer doesn’t even seem to have bothered thinking about what that might be. He’s content to go with the obvious. He doesn’t so much construct a plot as throw bits and pieces of one together; nothing that happens here makes the remotest sense, and the transitions are at best tenuous. He’s particularly lax in dealing with a subplot about Turner’s pregnant wife Sherri (Nia Long), who thinks that he’s off with a girlfriend while he’s actually engaged in his (unauthorized) imposture; it’s just dropped whenever it becomes inconvenient. And the lackadaisical helming of John Whitesell, whose resume includes such sterling specimens as “See Spot Run” and “Malibu’s Most Wanted,” can’t conceal the structural sags. He seems simply to have shouted “Action!” and invited Lawrence to do whatever the spirit moved him to. And the way some of the material plods on, one has to wonder whether the word “Cut!” is in his vocabulary.

No one in the supporting cast manages to escape Lawrence’s large shadow. Long and Emily Procter (of “C.S.I. Miami”), who plays the uptight Mrs. Fuller, are both attractive presences but just go through the motions, and the other FBI agents and all the villains are complete ciphers. The only supporting players that stand out are the ones Rhymer and Whitesell rely on most often: a dog called Pancho, which has scads of reaction shots (and a drunk scene!), and the youngest Fuller kid, Andrew–played by twins Preston and Trevor Shores–who has even more. When in doubt, cinematographer Mark Irwin was apparently instructed just to turn the camera on one or another of them. Otherwise his work is okay, as is the movie’s technical side generally, though Priscilla Nedo Friendly’s editing comes across as more than a mite choppy (probably due to the raggedness of the script). George S. Clinton’s music, as is his wont, is too bouncy and formulaic.

In sum, “Big Momma’s House 2” proves a ramshackle cinematic residence, though it’s fairly clean by today’s standards and is actually better than its predecessor, if only slightly so. But if one feels the need of a movie nanny this weekend, there’s a much better one out there. Her name is McPhee.