Johnny Knoxville reprises his JACKASS role as 86-year-old Irving Zisman in the story of a crotchety old man unexpectedly saddled with the care of his 8-year-old grandson Billy (Jackson Nicoll). The two generations of troublemakers soon develop a bond, as they hustle their way across the heartland of America on an outrageous road trip with a whole lot of hijinks and pranks on unsuspecting, real-life people - all of whom had no idea they were starring in a hidden camera comedy.

Liu Jin-xi (Donnie Yen) is a village craftsman whose quiet life is irrevocably shattered by the arrival of two notorious gangsters in the local general store. When Liu single-handedly saves the shopkeeper's life, he comes under investigation by detective Xu Bai-jiu (Takeshi Kaneshiro). Convinced that Liu's martial arts mastery belies a hidden history of training by one of the region's vicious clans, Xu doggedly pursues the shy hero-and draws the attention of China's criminal underworld in the process.