There's no shortage of dim-witted, foolhardy and empty-headed characters on the big screen.

Watch any horror film and at least one victim will venture into the dark to investigate a strange noise when common sense dictates you run in the opposite direction.

Inspector Clouseau blundered through various investigations yet somehow always solved the case, A Clockwork Orange featured a droog called Dim and Kevin Kline won an Oscar as numbskull assassin Otto West in A Fish Called Wanda.

Forrest Gump, one of cinema's great innocents, famously remarked that "stupid is as stupid does" and using that barometer, Dumb And Dumber To takes the art of moronic tomfoolery to new depths.

From the eye-watering opening gag of a DIY catheter removal, Bobby and Peter Farrelly's mindless sequel to their hit 1994 comedy embraces every crude, lewd and inappropriate set-up imaginable in its relentless pursuit of cheap, grubby titters.

If this is the future of comedy on film then the art form has flat-lined and I would strongly recommend for a Do Not Resuscitate order.

Jim Carrey and Jeff Daniels reprise their roles as best pals Lloyd Christmas and Harry Dunne, who mix up their words ("That's all water under the fridge") and are blinkered to the perils of modern life.

They merrily take a shower under the waste water pipe from a nuclear power plant.

For two decades, Lloyd (Carrey) has been consigned to Baldy View Psychiatric Hospital, where Harry (Daniels) visits and helps nurses to wash, dress and feed the comatose patient.

Thankfully, Lloyd regains the few senses he possesses and supports Harry through his own medical emergency: an urgent kidney transplant.

Since Harry is adopted, there is no familial donor and the future seems bleak.

Out of the blue, Harry learns that he fathered a child in 1991 with old flame Fraida Felcher (Kathleen Turner).

"Do you know what this means? You have a grown kid... with grown kidneys!" shrieks Lloyd.

The dim-witted duo tracks down the fruit of Harry's loins, Penny (Rachel Melvin), to her adopted parents: reclusive scientist Dr Pinchelow (Steve Tom) and his trophy wife (Laurie Holden).

Alas, Penny has already departed for a convention in El Paso to honour her father's ground-breaking work. So the simple-minded pals hit the road - and occasionally each other - in order to reunite Harry with his long-lost offspring and persuade her to give up her organ.

Dumb And Dumber To is a greater ordeal for us than it is for Harry and Lloyd, who are battered and bruised by misfortune.

The plot is nonsensical and includes pointless diversions including a brief reappearance of the Mutt Cutts dog van from the original picture.

Carrey and Daniels fling themselves into the fray with gusto, at the mercy of a script that lacks subtlety, sophistication or any discernible laughs.