Lieut. Dixon Piper (Ryan Phillippe, left) and Vicki St. Elmo (Kristen Wiig, right) team up with Will Forte's titular soldier of fortune in the action comedy MacGruber. (Greg Peters/Rogue/Alliance Films)

It's a project that should inspire fear in the hearts of cinema lovers everywhere. The mulleted action hero known as MacGruber (Will Forte) is being given the feature film treatment. Intermittently funny in the two-minute sketches on Saturday Night Live, this inept character – who proves with mind-numbing consistency that he can never defuse a bomb on time – seems as deserving of a full-blown movie as androgynous Pat.

MacGruber is that rarity: a movie based on a Saturday Night Live skit that actually improves upon the (thin) source material.

But in his directorial debut, SNL writer Jorma Taccone achieves the impossible: MacGruber the film improves upon the (thin) source material and manages to become that rarity, a dumb movie that's actually wicked smart.

At MacGruber's outset, we find this "real American hero" holed up in a cave. Having retreated from his life in special ops after the murder of his fiancée (Maya Rudolph), MacGruber preaches peace and sports some serious Michael Bolton locks. News of a stolen nuclear warhead draws him out of retirement, and forces the bungling agent to rustle up his faithful sidekicks, Vicki St. Elmo (Kristen Wiig), and military keener Lt. Dixon Piper (Ryan Phillippe, who deserves kudos for keeping a straight face throughout). Their hunt for the missing warhead leads them back to MacGruber's nemesis, Dieter Von Cunth (Val Kilmer), the arms dealer whose surname provides the punchline to many of the movie's profane jokes.

MacGruber was conceived as a send-up of Richard Dean Anderson's MacGyver, the rugged, stone-faced TV action man who could perform amazing feats of science, often with little more than a Swiss army knife, string and some chewing gum. Wisely sensing that this gag isn't enough to sustain an entire movie, Taccone sets his sights higher, using the movie's already-clichéd plotline as his jumping-off point to riff on every big, dumb action flick that thrived throughout the '80s.

Taccone hasn't missed a trick: the flashbacks to a traumatic past event, the obligatory assembling-the-crew montage, the pony-tailed villain and the shot of the hero striding away from an exploding car are all here. When he's not staging note-perfect Rambo moments, the director is recreating smaller period details, as in a scene where MacGruber cruises the streets in his red Miata, grooving to the soft-rock sounds of Gerry Rafferty's Baker Street.

Forte's hero shows an example of his resourcefulness in a scene from MacGruber. (Greg Peters/Rogue/Alliance Films)

Sight gags abound, and Will Forte goes for broke in all of them, particularly in a gutsy moment when he finds an inventive new use for a stick of celery. But it's Kristen Wiig who provides MacGruber's finest moments. An inventive comic who's also turning into a fine actor, she makes a real character out of Vicki St. Elmo. Underneath her feathered blond hair and blue eye shadow, Vicki is a quivering mass of nerves and self-doubt – she's such a mouse, she can barely make it through a coffee shop stakeout without having a meltdown. Wiig's so good in this scene, she makes you reassess every wispy, Heather Thomas type who appeared in '80s action movies, and wonder what these sidekicks could've achieved with a little assertiveness training.

MacGruber is still an SNL movie, with all of the fratboy humour that entails. F-bombs, scatological gags and homophobic jokes are ever-present, and the film also features the most crass sex scene since those Team America: World Police puppets hit the sheets. But the script's clever observations about pop culture help most of these gags fly. MacGruber's dick jokes serve a purpose – they're all part of Taccone's savvy critique of the bravado of every macho hero from Michael Knight to Matt Houston.

Far from a masterpiece, MacGruber is still written with enough smarts that it ends up feeling like some kind of achievement – a Saturday Night Live movie where the jokes actually detonate, right on time.

MacGruber opens May 21.

Lee Ferguson writes about the arts for CBC News.