NOTE: This spoiler was submitted by Andres.
The movie begins with an intro by Beavis and Butthead. In a nutshell, they explain how 3D works.
The actual movie begins now, with the cast walking in slow motion out of a light cloudy setting as an opera remix of the Jackass theme song plays. The cast is all dressed up in comical outfits (Bam is dresses as a cupcake and Ryan Dunn is dressed as a high school band member, etc.) Johnny Knoxville introduces the movie ("Hi, I'm Johnny Knoxville, welcome to Jackass!") and gets hit by an air compressor. The song changes to The Kids Are Back by Twisted Sister and all of the cast members are introduced as they get hit in different way.
- The High Five skit that is shown in the TV spots. They first get Ryan Dunn and then Ehren Mcghehey, who is carrying a tray full of soup. They then get Bam Margera, who is caked with flour and ends up on the floor.
- Steve-O is hit in the nuts by a baseball.
- Johnny Knoxville jet-skis into a field.
- The cast all take turns being slingshot into a ramp, which leads into a kiddie pool. Ryan Dunn is slingshot in a wheelbarrow and falls off and hits his nuts on the ramp. Preston Lacy runs into the pool and rips it.
- Bam Margera throws water at people and then punches them in the face with a boxing glove in super slow motion.
- Johnny Knoxville dresses up as an old man and an actor who plays his son go to buy a scooter. Knoxville "accidentally" starts up the scooter's motor and breaks through the store window. He then proceeds to steal the scooter.
- A professional football player tackles Johnny Knoxville. Seann William Scott makes a cameo in this scene.
- A pro football player kicks a football into Preston's face.
- Preston wears a plastic suit, which traps all of his sweat as he runs on an elliptical. Steve-O mops up his sweat and puts it in a cup and drinks it.
- Wee Man and his girlfriend who is also a little person go into a bar. Another little person gets into an altercation with Wee Man, claiming the girl is his girlfriend. He leaves angrily and returns with a gang of little people who then get into a fight with Wee Man. The police and paramedics arrive, who are also little people, to the astonishment of the bar patrons.
- Johnny Knoxville dresses up as an old man and an actress who plays his granddaughter go into public and make out. He grosses out a man who begins to chastise Knoxville for making out with his girlfriend.
- Bam Margera attaches a camera to his penis and pees on people.
- Ryan Dunn jumps a river on a rickety bike.
- Bam Margera is tricked into falling into a pit of snakes (he has a phobia of snakes). Bam begins to get desperate and cries.
- Ehren McGhehey's tooth is tied into Bam's Lamborghini. Bam drives fast and pulls out Ehren's tooth.
- Steve-O and Dave England play tetherball with a beehive instead of a ball. Dave gets scared and runs away, in pain from all the bee stings he got.
- Dave England colors his bottom as a hill, which is surrounded by a train set. He defecates (which, as someone says, went "three feet up in the air!") in slow motion as the poop cascades down.
- Johnny Knoxville runs into a pole and is bitten on his butt HARD by a dog.
- Chris Pontius attaches a toy helicopter to his penis and swings it from side to side.
- Johnny Knoxville throws a ball to Chris Pontius, who hits it with his penis. Bam then catches the ball with his mouth.
- The cast removes body hair from Phil Margera and Preston Lacy with super glue. They then glue Wee-Man and Preston together in a 69 position and rip them apart.
- Steve-O puts an apple in Preston Lacy's butt, removes it, takes a bite, throws up, and then puts it back in. A pig eats the apple out of Preston's butt.
- Johnny Knoxville shoots a dildo at the audience, which flies in slow motion through dioramas of cities, into a glass of milk and into Rick Kosick's cheek.
- People go into porta-potties where a balloon of blue paint explodes inside.
- Johnny Knoxville is rammed by a buffalo while roller-skating.
- Johnny Knoxville is painted to be camouflaged by a cardboard background and is hit by a bull.
- Preston Lacy asks a man to watch his dog while he goes into a store. Wee-Man comes out wearing the same clothes as Preston, and takes the dog back.
- Johnny Knoxville dresses like an old man and attaches a prosthetic leg to himself. A dog bites off the leg and runs off. The people around (its in a public place) are shocked.
- Ryan Dunn recreates the famous Maxell logo next to a jet engine. The cast then does things in front of the jet engine, like throw stuff at people and Bam pees in front of it.
- A man blows a party blower with his butt by farting. He also shoots darts out of his butt.
- The cast dresses up as prisoners and go through a hallway, which is filled with cattle prods and taser guns.
- Finally, Steve-O is strapped to a porta potty, which is launched in the air as the poop flies out in all directions.
The ending of the movie is a sequence, which starts when Johnny Knoxville blows up a piñata, which triggers an explosion in the room they are in. Water fills in like a tsunami and the cast swims along. Rip Taylor finishes the movie by saying some random stuff.
The credits show deleted scenes, old clips of the Jackass TV show, and old pictures of the cast and crew as kids.