After a shaky start, ‘Bad Neighbours’ blossoms, with inspired visual gags in excellent poor taste. That it never feels too dark is largely down to the sweetness of Rogen and Byrne. There’s a winning chemistry between them, and their predicament riffs neatly on the challenge of leaving youth behind. But the real star of the show is Efron, who relishes his chance to shine as a borderline-psychotic party boy.