Johnny Knoxville and his Jackass friends have an appreciation for the classics. In their movies they’ve paid tribute specifically to Buster Keaton and Busby Berkeley, and more generally to the many slapstick comedians and masters of choreography — of both the stunt and musical varieties — who’ve come long before them. Now with Bad Grandpa, they honor another old-fashioned hero, Allen Funt. This is basically a feature-length version of Candid Camera, with the pranks linked together through a basic fiction plot involving a horny old man (Knoxville in age-disguising makeup) on a road trip with his profanely precocious 8-year-old grandson. It’s not just that the shtick here is influenced by Funt’s long-running and oft-recycled hidden-camera shows. Most of the gags are familiar old tricks that likely were first done on Candid Camera or its copycats. In one well-worn bit, the grandpa, Irving Zisman, is having a tag sale in his home and shocks customers with a demonstration of his adjustable bed, which keeps collapsing, folding his body in seemingly harmful ways. Later he pays a visit to a UPS Store (or similar) to ship the kid to his deadbeat dad’s house in a giant box. I’m sure we’ve seen that kind of thing in numerous incarnations on various hidden-cam shows over the years.