Some good old laughs with Grandpa

The Jackass pranksters led by clown extraordinaire Johnny Knoxville take their wince-inducing brand of tomfoolery to the next level in Bad Grandpa.

They hang the usual daredevil stunts and bad-taste humour on a gossamer-thin narrative that is by turns touchingly sweet and eye-rollingly preposterous.

A couple of people involved in this mayhem are actors but largely, innocent passers-by are caught in the comedic crossfire.

Knoxville endures hours in the make-up chair to metamorphose into his signature character, badly behaved 86-year-old Irving Zisman, who starts the film in a hospital waiting room.

A female doctor approaches nervously.

“Your wife passed,” the medic says solemnly.

A woman sitting next to Irving offers her condolences.

“I thought she’d never die!” he cackles, confiding that Ellie denied him sex and is now in a better place.

The relationship between Knoxville and Jackson Nicoll as Irving's eight-year-old grandson Billy is lovely and the youngster scene-steals with aplomb, ad-libbing like a pro to the point that he makes his older co-star corpse.

There are some rip-snorting laughs to be had, and on that most primal and puerile level, Bad Grandpa is rather good.