“The Hitman’s Bodyguard” is about as close to a live-action cartoon as you’re likely to get this year — you know, the kind where someone blows a cannonball-shaped hole through Wile E. Coyote’s abdomen or a stick of dynamite reduces him to a pile of cinders, and the next thing you know, he’s up and chasing the Road Runner again. That’s not a style that works much of the time (see “Shoot ’Em Up” or early Arnold Schwarzenegger flop “The Villain”), but in the hands of “The Expendables 3” helmer Patrick Hughes — and more importantly, owing to the chemistry of stars Samuel L. Jackson and Ryan Reynolds — it makes for a delightfully ridiculous screwball action comedy.

The premise is simple: Jackson plays the hitman, Darius Kincaid, Reynolds plays his bodyguard, Michael Bryce, and they both need to get from London to the Hague without getting killed. That’s easier said than done as a seemingly inexhaustible army of Belarusian mercenaries do their best to rub them both out (to the extent of firing bazookas down Amsterdam canals) in order to prevent Kincaid from giving testimony against genocidal warlord Vladislav Dukhovich (Gary Oldman, projecting pure evil from his eyes, while the rest of his face is hidden behind prosthetic facial scars).

Normally, Bryce and Kincaid are bitter rivals. The former works to keep his clients alive, no matter how corrupt they might be, while the latter has led a very successful career in eliminating them. Kincaid has nearly killed Bryce no fewer than 28 times, but only once has he managed to eliminate someone Bryce was hired to protect (we’ll leave it to you to discover/guess who that might have been). Actually, it’s too obvious to write around, so skip this sentence if you’re afraid of spoilers: The movie opens with the botched job that ended Bryce’s relationship with Interpol agent Amelia Roussel (Elodie Yung) and cost him his triple-A status.

Now Bryce is back at the bottom of the food chain, living in his car and chauffeuring around white-collar deadbeats (like Richard Grant, who plays a hopped-up human target with a periwinkle Rolls Royce and a massive quantity of heroin stashed up his rectum). Meanwhile, with more than 200 kills to his name, Kincaid is at the top of his game when he gets nabbed visiting his wife Sonia in hospital (Salma Hayek like you’ve never seen her, saltier and more ferocious even than Jacki Weaver was in “Animal Kingdom”). “When she severed that dude’s carotid artery with a beer bottle … I knew right then,” Kincaid says, misting up as he remembers the violent couple’s bloody meet-cute.

With his beloved Sonia behind bars (it’s unclear why they can do this, although that flashback bar fight alone might justify it), Kincaid is willing to do anything for her release, even if it means risking his own life. That’s essentially what it comes down to, since his protection detail has been compromised, and Interpol’s assistant director (Joaquim de Almeida, playing it obvious) is working directly with Dukhovich to kill Kincaid en route to the tribunal — except that the evidence, when it finally comes, suggests that the hitman would’ve been fine just turning over access to his FTP site. No matter: It’s more fun trying to follow this “get me to the church on time”-style runaround, as Bryce is forced to make nice with Kincaid in hopes that it will give him a second chance with Amelia.

It’s no small challenge to multi-task two romantic subplots while also trying to manage the already-combustible dynamic between Bryce and Kincaid, and yet, Hughes pulls it off, thanks to a wildly irreverent script credited to Tom O’Connor — only his second to be produced, though earlier thriller “Fire With Fire” offers zero trace of this film’s comic touch, suggesting the work of other, unsung contributors here.

Jackson and Reynolds come to the table with very distinct star personae, and it’s clear the foul-mouthed comedy went through a serious rewrite to fit its two leads. Take Bryce’s line, “This guy single-handedly ruined the word ‘motherfucker,’” used to describe a man who has elevated the expletive’s usage to an art (the way actor Clay Davis has cornered the long, drawn-out “sheeeee-it”). In a film that’s only so-so in the action department, the real fun comes from the incessant bickering between the two stars — which falls somewhere between “Bringing Up Baby” and the combative, high-attitude style of Shane Black buddy movies.

The rest is so over-the-top, the only way to play along is to treat it as an elaborate Roadrunner cartoon, where Kincaid can take a bullet to the leg, extract the bullet himself (a Rambo-era cliché meant to convey gritty realism amid completely unbelievable violence) and jump off a roof, without so much as limping. An early staircase shoot-out pales in comparison to last month’s “Atomic Blonde” (although this movie makes better use of ’80s songs), while other sequences are either too heavily computer-assisted or shot with blatant stunt doubles — as when Bryce wears his helmet for the entirety of a drawn-out motorcycle chase.

Another scene parodied over the end credits features an unflinching Reynolds superimposed against the Dutch capital, unfazed by the brutal bloodbath unfolding behind him. Did the actor even go to Amsterdam? That much isn’t clear, though the crew certainly did, with units in the Netherlands, Bulgaria and the U.K. lending great scenery and serious production value to one of Millennium Media’s all-time most entertaining actioners. Coming from a company known for pyrotechnic B movies, “The Hitman’s Bodyguard” is better than much costlier studio-backed equivalents (such as “The Mexican,” “The Bounty Hunter” and “This Means War”).

Plus, it comes with the added bonus of listening to Samuel L. Jackson sing the original (Oscar-eligible?) ditty “Nobody Gets Out Alive,” also featured over the closing credits. It’s a nice display of versatility from an actor who is very comfortably within his wheelhouse here, ultra-cool and cockroach-unkillable as he laughs off every scrape. Reynolds plays it cute, but Jackson steals the show, putting Bryce in his place with the existential question — the kind philosopher-hitman Jules Winnfield might have asked in “Pulp Fiction” — about which of the two men has chosen the more righteous path: “he who kills evil motherfuckers, or he who protects them”?