Jackson Nicoll and Johnny Knoxville in Bad Grandpa.

The early days of cinema had Harold Lloyd and Charlie Chaplin risking their lives with daring stunt work, all in an effort to make moviegoers laugh.

Today, we have the immortal, deranged, considerably less-refined Johnny Knoxville.

Knoxville has tried to parlay his Jackass fame into an acting career—but he hasn’t exactly been setting the world on fire. Because huge paychecks are tempting, Knoxville has therefore returned to the Jackass well with movies—and his body has paid a tremendous toll. The man has thrown himself into the path of buffaloes and bulls to score good laughs—and, oh man, has he gotten those good laughs.

As big as those checks can be, internal bleeding and broken limbs lose their luster after a while. So now we get Bad Grandpa, a sort of Jackass movie that has a narrative mixed with hidden-camera stunts (very much in the tradition of Borat). Knoxville plays Irving Zisman, an 80-plus-year-old letch who has shown up in Jackass skits.

The “plot” involves Irving begrudgingly taking his grandson, Billy (Jackson Nicoll), on a road trip after the kid’s crack-addicted mom goes to jail. Along the way, of course, the two get themselves into all sorts of hijinks. Director Jeff Tremaine (who has piloted all of the Jackass films) includes some scripted scenes between Knoxville and the kid that are actually quite sweet at times. However, those scenes are mere buffers before and after the Jackass-type madness.

Early in the film, Irving is presiding over his wife’s funeral. He has gotten an audience full of strangers, including church-choir members, to sit in and help him mourn. The results are hilariously disturbing—and just about as evil as any hidden-camera gag has ever been.

Nicoll is quite the little scene-stealer. Knoxville has to labor for laughs, subjecting his body to a rapidly folding bed and a faulty kid’s ride that shoots him through a window. Nicoll needs only to put on a bemused face or keenly deliver a zinger to show up his older co-star.

The film’s best moment involves one of those disgusting child beauty pageants—and it belongs to Nicoll. The kid winds up in a rather convincing little princess getup and politely goes through the motions of a pageant—until the talent competition. That’s when he strips off his sailor outfit and does his best stripper dance to “Cherry Pie.” Nicoll flailing away on the ground while Knoxville showers him with dollar bills will surely contend for Funniest Moment of the Year honors.

If you go to this looking for Steve-O or Bam (Knoxville’s Jackass partners), you will be disappointed. The boys are nowhere to be seen, although co-producer Spike Jonze and actress Catherine Keener show up, unrecognizable in heavy makeup.

Speaking of makeup: Bad Grandpa should actually be a legitimate Oscar contender in that category. Knoxville’s old-age makeup is killer; I’m not surprised that he’s able to trick a lot of onlookers during the hidden-camera stunts. It’s some damn fine work, much better than the old-age makeup worn by Leonardo DiCaprio and Armie Hammer in J. Edgar. Those guys looked like California raisins.

There are a lot of good gags, as well as a few clunkers. Irving’s visit to an all-male dance club results in some ball-hanging fun, and a fart contest with his grandson has some hilariously explosive results. I also liked a bit involving a virtuous motorcycle gang, and a series in which Billy asks strangers on the street to be his new daddy.

Stick around for the credits, which feature some funny outtakes—and, best of all, scenes of the duped stunt victims finding out they are in a movie. It’s actually a relief to see those poor funeral attendees get the news.

To get primed for Bad Grandpa, I watched a lot of Knoxville’s old stunts, including the various hits he took from large animals. Those will always be funny, and I could watch them 50 times in a row and laugh each time. However, I would prefer to see him dial it down in future film ventures, as he does in Bad Grandpa. It’s the sort of movie that should please his fan base while blessedly lowering his risk for early, bone-smashing mortality.

Bad Grandpa is playing at theaters across the valley.