Adam Sandler and R-rated comedies usually don’t go together. The last one he did was Judd Apatow’s criminally underrated “Funny People” in 2009, a movie I can only assume was too cerebral to be seen as a Sandler movie.

And while “That’s My Boy” is in no way cerebral, it’s nice to see a bit more “dirty” from an actor who’s long been playing it safe.

His character, Donny, begins the film as a thirteen-year-old seduced by his hot math teacher (Eva Amurri Martino, the daughter of Susan Sarandon) and left to raise a son when she’s caught and sent to prison. The scandal turns Donny into a national celebrity, one who’s coasted ever since into being a deadbeat adult who owes the IRS.

With no other option, a sleazy tabloid news show offers him fifty thousand dollars if he can produce a reunion between him, his son and the incarcerated mother. Only the problem is the estranged son, Han Solo, now a successful number cruncher who re-named himself Todd (Andy Samberg), wants nothing to do with either of them and is looking at his upcoming wedding to a beautiful woman (Leighton Meester) and a big promotion to help him turn the page on a sleazy past definitively.

Not surprisingly Donny shows up just before the wedding (introduced as a friend since Todd has already told everyone both parents are dead) just in time for some drunken antics and father-son bonding.

Even when the jokes are at their grossest you can tell Sandler & Co. are having some infectious fun here. Everything from masturbation, urine, vomit, incest, breasts, genitals, sex with geriatrics, and racist Asian jokes make up this stale patchwork of tastelessness, all of it handled with sloppy direction by Sean Anders.

Yet as bad as all this is, it’s outrageous and as things move along, “Boy” gets to be wildly entertaining.

Not unhelpful is the fact that “Boy” holds genuine sentiment. Sandler and Samberg make up a good pair, the former doing a kind-of Boston-accented Al Pacino who can’t go a couple of sentences without saying something profane while the later is meant to be your average straight-laced pushover in need of a spine. There’s a compelling subtext to this relationship, that of a father trying to make up for the parenting mistakes of his youth, which include letting the kid balloon to four-hundred pounds and giving him one of the most embarrassing tattoos, like, ever.

Along the way, Milo Ventimiglia (“Heroes”), camping the hard-ass army sergeant who has it out for Todd, Tony Orlando, Todd’s boss, and Vanilla Ice and Todd Bridges, thankfully playing themselves, show up for some laughs, too. Like I said, nothing cerebral going on here, but as far as Sandler movies go, this one at least has a childish ambitiousness.