The final instalment of the Diary of a Wimpy Kid films has been highly anticipated by fans of the series, and with good reason; the premise is based on the wimpy exploits of a particularly wimpy sort of wimp, designed to make all but the most pathetic child feel superior and smug. He’s in love with a girl approximately eight levels hotter than him, has a best friend who worships him, a harried mother and a father who doesn’t really like him at all. Also, a baby brother who resembles the lovechild of Rupert Grint and a chimpanzee.

In a race to beat the obviously imminent transformation of lead actor Zachary Gordon’s physique from boy to man, the last two books of the series were converged into one big summer blockbuster, and you can tell. The lack of any sort of nuance or sense of farewell is a shame in a franchise which is clearly beloved of its target audience. The film follows the exploits of Greg Heffley (Gordon), and his madcap adventures with dough-for-brains best friend Rowley (Robert Capron), centred around avoiding his nature-junkie father and his alarmingly shrill mother’s death-by-Dickens summer book club. His “sexy” older brother Rodrick is played by a rather engaging Devon Bostick (Saw VI), and of course, the initial plot thickens around the brothers’ pursuit of two vapid blonde sisters. Like miniature Hugh Hefners, the two of them put on their velvet bathrobes and PervSlippers and end up following Holly (Peyton List) and Hilary (Emily Holmes) into a swanky country club where they are most definitely not members. Shenanigans ensue, people fall out, the dog comes along and chews stuff and someone’s parent utters the dreaded “I’m just so disappointed in you,” the inevitable formal event rolls around to wrap up the plot. By this point, you are so bored you are considering beating the child(ren) you have brought with you just for an excuse to leave, even if it is to prison.

AND THEN IT HAPPENS.

The greatest modern-day musical performance of our generation comes out of nowhere and smacks us in the face, and it is glorious and all the little girls in the cinema start cry-retching in a way which is hilariously uniform. Greg’s brother Rodrick is in a band rather immaturely called Loded Diper – we laughed, sorry to say – which showed no potential whatsoever for the metalhead remix of Justin Bieber’s Baby, in a pink-ballooned marquee as the tarted-up object of the song tries to wipe away the tracks her tears leave on her cake-smeared face. It’s one of those things that is so agonisingly shit it just comes full circle and ends up FABULOUS. Unfortunately, the film is so new that you can’t actually find any bootlegged footage of it yet, so instead, have this gem from the second film.

Films like this make us grumpy, unless very well-executed, because children bloody well suffer. They have to go to school in horrible primary colours, learn how to play The Entertainer on a shoebox-sized rental violin, play stalkerly games likes Kiss Chase and Stuck in the Mud which only serve to create future sex offenders, and socialise with other equally putrid, borderline sociopathic tiny humans until they eventually leave puberty and become people. God forbid they get to live a little longer in shiny CGI lands where there are fairies and goblins and magic and dinosaurs – encouraging schadenfreude in vulnerable brains riddled with Ritalin and other crack derivatives is just sad.

Other than that, the main problem with Dog Days is its total lack of heart. DILF he may be, but Papa Heffley (Steve Zahn) just doesn’t sell a desire to build a relationship with his son, and his mother is plainly in need of more money to buy ugly glasses, so phoned-in and dimensionless is her performance. Bright spots, however, include the very experienced Gordon, whose air of mismanaged Jewish guilt serves him well, and the upstanding young men he has befriended; bonus points go to Ginger Ninja extraordinaire Grayson Russell, who plays the neeky Fregley with a good humour far beyond his years. Other than that, you’d be better sitting any sprogs in your vicinity in front of The Incredibles or some other solid Pixar creation if they refuse to learn how to use a VCR; THAT dad is a lad.