Jackass Presents: Bad Grandpa is no doubt critic-proof. Its knowing crassness will protect it against every brickbat; fans will form themselves into impregnable armour. Full Metal Jackass. You either love or hate the thought – let alone the fact – of Johnny Knoxville dressed and made up as an old man, pranking his way across America with a mischief-complicit grandson.
I liked the Little Miss Sunshine-style moppet contest, invaded for real by the boy in drag doing a bump-and-grind striptease. (The Midwest Mrs Worthingtons succumb to seizures.) But at 90 minutes it’s too much of a slight and, at times, self-consciously naughty-minded thing.