Given the quality of his recent movies, one Adam Sandler is bad enough, but “Jack and Jill” proves how much worse it can be when there are two. In male garb the gravel-voiced comic, whose work has gotten ever more lazy over the years, plays—if that verb can be used to apply to his lackadaisical posturing—Jack Sadelstein, an LA advertising executive who makes TV commercials. He has a nice home, a nice wife (Katie Holmes) and two cute kids (Elodie Tougne and Rohan Chand). But he’s got two problems. One is the insistence of his biggest client, Dunkin’ Doughnuts, that their next production star Al Pacino, who’ll prove hard to get. The other is that he’s expecting the arrival of his rowdy twin sister Jill, whose holiday visits always bode disaster. Those of us who have sat through this wretched mess can attest that’s certainly the case in this instance, anyway.

Sandler plays Jill in drag, of course, with one of those screeching, nasal voices of his that were ear-piercing in three-minute Saturday Night Live sketches and have always been insufferable in larger doses on screen. She’s an abrasive loudmouth and clueless dolt, but we’re supposed to believe that she’s actually a sweet person—to everybody but Jack. Of course, deep down they really love one another, and the only thing in the script by a trio of Sandler regulars worse than their screaming altercations are the sequences in which they bond and talk the baby-like gibberish only they can understand. Well, perhaps there’s one other thing—the knowing put-downs of Jack put into the mouth of his adopted son Gary (Chand), which always serve as the sign that a scene is about to fade to black.

But the familial part of the plot is only half of the picture, and it’s in the other that it goes from conventionally terrible to surrealistically awful. It concerns Jack’s efforts to persuade Pacino, who does a take-off of himself, to do the commercial. That’s complicated by the fact that Al does a “love at first sight” when he encounters Jill, and demands that Jack set him up with her. In what’s supposed to be the high point of hilarity Jack impersonates his sister for a date with Pacino; but of course though that leads to a narrative crisis, it elicits no laughs.

The mystery about “Jack and Jill” isn’t how such a piece of crude, stupid slapstick could come from the Happy Madison stable—it specializes in such junk (after all, its immediate predecessor was “Bucky Larson”). So you won’t be surprised to learn, for instance, that there’s a flatulence sequence that rivals the one in “Dumb & Dumber” in its crassness. Or that there are lots of hideous secondary characters, including a particularly grotesque old woman played by heavily made-up Eugenio Derbez, who also serves as her gardener grandson Felipe—who supposedly is attracted to Jill, too.

No, the puzzle is how Sandler attracted so many people to do bit parts in the movie. One expects appearances by such Sandler pals as David Spade, Dana Carvey, Norm MacDonald, Tim Meadows and Nick Swardson. And others, like Regis Philbin, John McEnroe, Bruce Jenner and Drew Carey, don’t have much to lose.

But how to explain Pacino’s decision to sacrifice whatever shred of professional dignity he has left in what amounts to a frightful co-starring turn, or the truly horrendous cameo by Shaquille O’Neal? And whatever possessed Johnny Depp, of all people, to play a scene courtside at a Lakers game that makes him look like an idiot? Yes, he gets some chuckles, but at what cost?

Such questions must be left to the ages. Suffice it to say that everyone involved in “Jack and Jill”—except for Sandler and hack director Dennis Dugan, both of whom seem incapable of shame—should be properly embarrassed at their participation. That includes the technical crew, from cinematographer Dean Cunday down to the most humble gaffer, and the real-life twins whose personal anecdotes at the beginning and end of the picture are meant to be endearing. (The shamelessness of the entire enterprise is telescoped early on by shots of infant twins that are obviously designed to elicit “aw”s from the most susceptible members of the audience.)

After suffering through “Jack and Jill,” this reviewer quickly cleansed his cinematic palate with a DVD of Laurel and Hardy’s “Twice Two,” in which the boys play one another’s wives. It’s not one of their better shorts, but it’s still a lot better than this. Those guys were as naturally funny as Adam Sandler isn’t, or perhaps just no longer is.