The three times Adam Sandler has headlined an R-rated film in the past, said projects have been unorthodox fare for the usually commercially-minded performer: 2009's not-very-funny Judd Apatow stumble "Funny People," 2002's Paul Thomas Anderson love story "Punch-Drunk Love," and 1996's buddy actioner "Bulletproof." Thus, "That's My Boy" marks Sandler's first foray into a wholly mainstream comedy (produced by his Happy Madison shingle) that also happens to require a parent or adult guardian for theatergoers under 17. Let loose to do whatever he likes, Sandler goes hog-wild, turning a heartfelt if calculated father-son story into a crass, obscenity-filled free-for-all that, unfortunately, wavers throughout between irreverent and incendiary. Even as it evokes a handful of good-sized chuckles, there's also something unsettling, even vicious, about the amount of lives the screenplay by David Caspe (TV's "Happy Endings") all but destroys on its path toward rekindling the bond between one grossly irresponsible man and his far more put-together offspring.

Twenty-eight years ago, 13-year-old Donny Berger (Justin Weaver) made national headlines after getting caught in a sexual relationship with his teacher, Ms. McGarricle (Eva Amurri Martino). Unapologetic over her love for him, she was sentenced to thirty years in prison and promptly had his baby, a boy he named Han Solo. Cut to present day, Donny (now played by Adam Sandler) is a beer-swilling, directionless forty-year-old in hot water over a tax evasion charge. Owing the IRS $43,000 or risk going to jail himself, Donny begins to formulate a scheme when he learns that his estranged son, now a successful Manhattan hedge fund manager who has renamed himself Todd Peterson (Andy Samberg), is due to be married to Jamie (Leighton Meester) in Cape Cod. Having lied about both his parents being dead, Todd is horrified when Donny shows up. They haven't seen each other in close to ten years, but now Todd must carry on the charade that Donny is his best friend in front of the entire wedding party and Jamie's well-off family. Behind closed doors, Todd wants nothing to do with his dad, but little by little he comes to decide reconciliation might be a possibility. What he doesn't know is Donny's original reason for showing up—a purpose he no longer feels right at all about, even as the deadline for payment looms nearer.

There are many humps to climb over in order to buy into "That's My Boy." The first is in the numbskull conflict of the plot, the sort that could be solved in a matter of minutes if only the characters were written up to the level of human beings with normal intelligence. Would it really be so difficult for Todd to sit Jamie down and explain to her his embarrassment being connected to a high-profile court case and a dead-beat father he never got along with? Nonetheless, the rest of the characters gullibly go along with what they're told, all the better to look surprised at the end when the truth is finally spoken. Also troublesome, at least at first, is Adam Sandler's (2011's "Jack and Jill") insistence in putting on a silly voice for Donny—a voice that he did not speak with as a kid and now sounds like a Boston accent by way of a speech impediment. When some of the details of Donny's parenting skills surface, one understands full well Todd's desire to distance himself (the warped New Kids on the Block tattoo covering his entire back, which Donny made his son get when he was eight, might be the final straw).

Tossing aside all of these contrivances and taking the movie for what it is—little more than a series of comic set-pieces—the film plays decidedly better. No one is safe from director Sean Anders' (2008's underrated "Sex Drive") caricatured gaze, so much of the raunchy, politically-incorrect humor hinging upon racial and societal stereotypes that it ceases being offensive because everyone in one way or another is open for ridicule. Better, perhaps, is its fish-out-of-water material, and the way that various people react to Donny's loutish personality. A bachelor party trip to a men's spa is a highlight as it takes its time and raises the bar, culminating in an outrageously delivered one-liner from Ana Gasteyer (2008's "The Women"), playing the outwardly relaxed, inwardly sexually frustrated spa guide Mrs. Ravensdale. This is followed by an unfiltered night on the town (with Donny's pal Vanilla Ice in tow) that must be seen to be believed. Also very funny: a running gag involve the old "wazzup!" Budweiser ad and a scene where Todd tries to stop Grandma Delores (Peggy Stewart) from picking up the very tissues Donny used to masturbate to her photograph. It's so wrong, but, in context, very right.

Andy Samberg (2011's "What's Your Number?") is likable playing straight guy Todd, if still not fully comfortable in front of a film camera portraying a character for longer than the length of a skit, while Leighton Meester (2011's "The Roommate") is appropriately close to spiteful even before some of the skeletons in Jamie's closet are revealed. Why Todd would want to marry her to begin with is a question not satisfactorily disclosed. Playing the younger and elder version of Ms. McGarricle, real-life mother and daughter Susan Sarandon (2012's "Jeff, Who Lives at Home") and Eva Amurri Martino (2008's "The Life Before Her Eyes") are gorgeous dead-ringers for one another and prove to have a sizable sense of humor. Usually potent forces like Will Forte (2010's "MacGruber") and Rachel Dratch (2011's "Just Go with It"), meanwhile, are squandered with little to do as best man Phil and his wife, the two of them headed for a heartbreak.

True to form for most Sandler comedies, "That's My Boy" has a fantastic soundtrack of '80s and '90s gems (The Replacements' "Unsatisfied" and Van Halen's "Dance the Night Away" are used especially well) and a fair share of amusing moments sprinkled through the juvenilia. As a limits-pushing R-rated picture, however, it arguably goes too far, making light of some awful subject matter such as infidelity and incest that's more uncomfortable and mean-spirited than cause for hilarity. As the audience is manipulated into caring about the fate of Donny and Todd as they make amends and realize how happy they are to be a family again, it comes at the expense of shattered lives director Sean Anders tries to sweep away with no one noticing. By the end credits, an entire family has been ripped apart by horrific secrets of a taboo nature, and another couple with children are thrown into immediate domestic jeopardy when one of them is discovered to be unfaithful. Treated like punchlines when they are anything but, the film perversely delights in these people's downfalls. Less would have been more. It is for this reason, then, that it's impossible to warm up to "That's My Boy," despite its many inspired bits. Whereas Adam Sandler is often accused by critics of not trying hard enough, here he tries too much, and pays roughly the same consequences.