Be suspect of movies that are infamous before they even hit theaters.

The “they did WHAT” anticipatory glee is generally bound to be a letdown — especially when the big joke is someone getting a disease. In the off-chance that you’ve managed to stay blissfully unaware of the gag, I won’t go into any more specifics. Needless to say, it does indeed happen, it is brazen, and it will leave you dumbfounded.

Whether or not the joke will also elicit a laugh is the big question, though. It’s one that applies to much of the humor in the movie, too, which starts out with a Bill Cosby jab and steamrolls on from there.

The plot finds a sweet-hearted, dimwitted, working-class Northern Londoner (Sacha Baron Cohen’s Nobby) reunited with his younger brother, Sebastian (Mark Strong), after 28 years apart. Sebastian is now a top spy and assassin, with a hardcore shaved head to match his ruthless attitude.

Nobby’s ill-timed reunion with his long-lost kin puts Sebastian’s job, and life, in jeopardy — tethering the two for the remainder of the movie as they try to clear Sebastian’s name and save the world.

The jester and the brain pairing is a time-tested formula that on paper seems pretty foolproof. The way it’s carried out here, however, feels plucked from a 1990s movie that’s still experimenting with the novelty of gross-out humor, know-it-all storytelling, and just how far you can coast on the charisma of a star.

Strong plays it straight, but isn’t nearly as memorable as Jason Statham’s turn in “Spy.”

Baron Cohen, who also co-wrote the movie, is sort of lovable as Nobby with his daffy, crooked-toothed smile, Oasis hair, teeny potbelly, and grungy socks and sports sandals.

Nobby is such an earnest dolt that even the Bill Cosby joke is almost OK. The presumed hilarity of his preference for curvier girls (Rebel Wilson and Gabourey Sidibe among them) is similarly made more tolerable by his unending sincerity.

In fact, flashbacks to Nobby and Sebastian’s hooligan youth are fairly touching and effective, too, as is the thru line about class and the worthiness of Nobby’s rowdy, soccer-loving, out of shape buddies — or, as he later puts it, “the scum who keep the ‘Fast & Furious’ franchise alive.”

But then there’s a joke about pedophiles at Legoland, or an ancient “Saturday Night Live” Celebrity Jeopardy riff on the word “therapist,” and your jaw is once again on the floor.

It’s almost impossible to tell whether you’re laughing at or with a particular party, if you’re even laughing at all. Ultimately, the jokes are more stupefying than funny, and no one’s anatomy is safe from a gratuitous close-up, whether it’s that of a wild animal or an Oscar nominee.

Speaking of Oscar nominees, “Captain Phillips” star Barkhad Abdi even pops up for a spell as a heroin dealer.

It’s hard to give yourself over to a certain type of humor when you’re still recovering from the shock of what you just saw or heard. And boy, does “The Brothers Grimsby” push those boundaries, over and over and over again.

Whether or not that’s a good thing can only really be determined by the individual viewer, and in some corners of the world, “The Brothers Grimsby” might actually be well-positioned to become a cult classic somewhere down the line, even if Nobby does look pretty minor in a legacy that includes Borat and Ali G.

In the spy spoof realm, I’d rather just rewatch last year’s almost equally raunchy, but infinitely cleverer “Spy.”