“Kingsman: The Secret Service” opens Friday at Point, Eastgate and Star Cinemas. R, 2:09, three stars out of four.

I’m not saying I’m proud to have enjoyed a movie in which a dapper Colin Firth shoots, stabs, bludgeons, immolates and electrocutes about a hundred people while the guitar solo from “Freebird” plays on the soundtrack.

I’m just saying I did.

Matthew Vaughn’s shamelessly entertaining spy goof “Kingsman: The Secret Service” is bloody, crass, and snotty, and tramples all over one of my favorite genres, the British spy movie. And yet it does all this so cheerfully and charmingly, winking constantly at the audience, that I found myself won over.

Firth plays Harry Hart, code named Galahad, a member of a secret society of international spies called the Kingsmen who operate out of the back of a London tailor shop and, based on their bespoke pinstriped suits, probably get an employee discount card there. When one of their members falls, the surviving members each find a possible replacement, typically an upper-class Cambridge type to fit in with the posh mahogany-and-leather environs of the Kingsmen.

But Harry has a long-standing debt to a Kingsman who died in the line of duty 17 years ago. So he finds his old colleague’s son, Eggsy (Taron Egerton), a cheeky working-class punk doomed to a life of petty crime, and recruits him for the job. Under the watchful eye of Merlin (Mark Strong), the Kingsmen’s resident Q, Eggsy has to outwit and outlast his snobby rivals for the job. (A tremor of class struggle runs throughout “Kingsman,” literally exploding in the last act.)

Meanwhile, every spy organization needs its supervillain, and “Kingsman” has it in Richmond Valentine, a tech billionaire whose equal parts Steve Jobs, Russell Simmons and Daffy Duck. Played, as he must be, by Samuel L. Jackson, Valentine has a secret plan to “save” the world that involves mysterious SIMM cards he’s implanted in every cell phone and tablet in the world. He’s also got one of the secret mountainside bases that have been out of fashion in spy movies ever since “Austin Powers” made fun of them, and a dilly of a henchman in Sofia Boutella, whose blade-like prosthetic legs can slice a man in half.

What Vaughn’s “Kick-Ass” did to the superhero genre, “Kingsman” wants to do to the spy movie genre (call it “Kick-Arse”) — not so much satirize it as crank up the volume until the cliches start to crack. But while I loathed “Kick-Ass,” finding it petty and mean, there’s a giddiness to “Kingsman” that’s much more appealing. The violence is so cartoonish and the characters are so ridiculous that it’s all just a joke, but one that we feel in on.

Eggsy seemed like a grating character from the trailers, but Egerton makes him very affable and human under his dime-store bling. And Firth makes the most of the film’s central gag, seeing the upright Mr. Darcy sigh a little, put down his Guinness, and become a one-man killing machine at the drop of a bowler hat. “Manners maketh man” is Harry’s motto, which is ironic for a movie that has no manners at all, and still wins us over.