Trailers made this film look like a cross between Jackass and the films of Sacha Baron Cohen, and the thing I was most curious about was how it would stitch all the 'real response' stuff together with a functional narrative.

It does so simply by telling the story of a crotchety old dolt (Knoxville) who has to drive his grandson across the country to his redneck dad when his trailer trash mother gets put in prison, and the relationship they form along the way.

Take away all the Jackass tricks and laughs and ignore most of the mature-age plot developments and the discovering-we're-family premise has been done to death a million times.

Which just leaves the Jackass-style gags to carry the rest of the film. The writers (all the members of the Jackass team including usual director Jeff Tremaine) do so by setting up episodic scenes where the unrecognisable Knoxville as the belligerent title character can shock and horrify bystanders with episodes of violence, vice, bowel movements and everything else Jackass is famous for.

There are enough laughs to keep you mildly entertained if you like the kind of style Jackass produces, but the problem is hardcore fans of that style will be bored during the scenes where the story's advancing. If that style isn't your cup of tea, without an original or engaging story there's not much here for you.