Just when you thought it was safe to see an Adam Sandler movie, the crafty comedian has reversed course and returned to plowing the field of lowbrow comedy, in which he’s a Perfect 10.

I was never a fan of Sander’s output in the 1990s, but his performance in Paul Thomas Anderson’s Punch-Drunk Love turned my head in 2002, and since then he has demonstrated a pleasant degree of ambition to go along with his audience-pleasing schtick. Splanglish, Reign Over Me, I Now Pronounce You Chuck & Larry, You Don’t Mess With the Zohan, and Funny People may have all had fatal flaws, but, taken as a whole, the films indicated a willingness to experiment and take on a broader range of material. Grown Ups, his latest alleged comedy, is a lazy return to the 20th Century. More accurately, it’s a retreat into 19th Century vaudeville, filled with pratfalls, insult humor, and antique jokes that had to be restored before they could be dusted off.

It’s meant to be a Saturday Night Live reunion, with Sandler joined by former cohorts Chris Rock, David Spade, Rob Schneider, Maya Randolph, Colin Quinn, and Fred Wolf (who co-scripted with Sandler). Kevin James stands in for the late Chris Farley, with Salma Hayek and Maria Bello inserted as improbable wives to add a dash of beauty to the proceedings.

Instead of a reunion, though, it feels like the script has been hibernating in a musty corner since it was rejected as a skit. Maybe the idea of a junior high school basketball team reuniting after the death of their coach would have been funny if it was packed into a fast-paced five minutes. Dragged out to interminable length with limited imagination, it quickly becomes a chore to sit through.

To be absolutely fair, I did laugh several times during the movie — the kind of involuntary laughter that comes when someone rubs your funny bone the right way — but there is no wit on display, no joy to be shared from the experience. Many people at the preview screening I attended were laughing throughout the movie — but that just shows we have different taste.

We’re asked to believe that these five men are lifetime friends, but on what basis are they friends? Is it simply the inertia of laziness? They have little in common, and we’re given no clue as to what has held them together in the 20 years since they played together as teammates. Friends of convenience are commonplace in the school years, but if there’s not something else to bond them, the friendships gradually melt away. That’s natural; that’s part of life. We can even imagine that several of these actors are still good buddies because they share a common world view, or because they work together — or maybe their wives are friends, who knows? But the characters they’re playing on screen? No reason they’d seek out each other’s company for more than five minutes.

Does that matter? Only in a character-based comedy, which Grown Ups strains mightily to be after the slapstick runs dry. Without convincing characters, with precious little comedic chemistry on display, without much of a story to tell, with too much reliance on cute kids and cheap gags, and with no visual panache (and I so adored director Dennis Dugan as an actor!), the movie begins to resemble Sex and the City 2.

Adam Sandler, you’ve had your vacation and given your old friends a nice paycheck. Time to get back to work.

[Grown Ups opens wide today.]