NOTE: This spoiler sent in by Daremaster Spoodle - Seriously, that's the name he gave me...
The movie starts out much like the first one did, with slow motion shots of the Jackass crew running down the street during the opening credits. Knoxville, Bam Margera, Ryan Dunn, Dave England, Wee Man, etc. are running down the street from some bulls, and each one gets knocked over/runs from the bulls/almost gets gored in hilarious fashion.
The first skit after that is "The Puppet Show", where Chris Ponitus (aka Party Boy), disgusing his penis as a mouse, puts it through a hole inside of a snake tank, where it is bitten by a snake, obviously.
After that comes Spike Jonez dressing up as an old woman with fake sagging boobs, and keeps exposing himself in public. These skits come up several times throughout the movie.
Then Steve-O jams a huge fish hook through his lip, and uses himself as bait to attract sharks in "Man Fishing". Steve-O almost gets bit and kicks one of the sharks away with his foot. Around that time is "The Valentine", where each member of the Jackass crew reads a fake valentine on a wall, but it's actually concealing an automatic boxing glove which hits them, controlled by Knoxville.
The more gross skits in the movie, in case you want to cover your eyes, are "The Fart Mask", where Steve-O puts on a diver's mask connected to Preston Lacy's butt (Preston farts and Steve-O pukes in the mask), "The Dollhouse" (Dave England poops in a miniature toilet inside a dollhouse bathroom), another skit with Dave England where guest stars Three Six Mafia pay him $200 to eat horse manure, and another stunt where the Jackass crew obtains horse semen and tries to drink it.
Also, in "The Magic Trick", guest star, director John Waters (Pink Flamingos), hosts a "magic trick" to make Wee Man disappear, by having a huge obese woman jump on him in bed, totally covering him ("WOW! Where did Wee Man GO?").
Then there's a skit where Johnny Knoxville, and, I think Ryan Dunn, go into a plastic ball kiddie pool with two anacondas inside. Both are badly bit and bleed like stuck pigs while trying to get the huge snakes out.
"The Switcheroo" is a hilarious skit where the crew dresses up Preston Lacy to look like Phil Margera (Bam's dad), and switch him with Phil in bed while April Margera is sleeping (Bam tells Preston, "don't be afraid to get frisky!")
Johnny Knoxville and the crew also put rockets and air compressors on various objects trying to fly over the English Channel. None of them work very well until Knoxville has a huge red rocket constructed. It fails on the first attempt, almost exploding, but on the second try Knoxville flies really high and far while riding the rocket.
Somewhere in the movie Steve-O puts a leech on his eyeball visiting a medicine doctor in India.
Also is the "Toro Totter", where Knoxville, Ryan Dunn, Bam Margera, and I think Chris Ponitus get on a four way teeter totter to play a game of "chicken" with a bull. The last one to stay on the teeter totter wins (Knoxville does). Ryan Dunn panics and jumps of the totter, and is running so fast he smacks his head into a wall. Bam Margera says "Fuck this!" and also runs off, and I'm pretty sure that Ponitus gets badly gored.
There's also various skits, like in the first movie, of random stuff (like Preston chasing Wee Man in their underwear again). Then there's "Medicine Ball Dodgeball", where everyone gets hurt really badly. Then Knoxville, Ryan Dunn, and Bam Margera allow a huge non-lethal anti-riot mine to be used on them. Knoxville is still standing and actually enjoys it, but Bam and Ryan are very badly hurt.
Knoxville also dresses up as an old man, much like in the first movie, and pranks people by making it look like he's giving a kid cigarettes and booze. He also has fake testicles constructed to hang out of his shorts, and that skit is hilarious (at one point a dog bites on to them and won't let go, it's TOO funny!)
Then comes "The Gauntlet", where the guys skate, ride bikes, etc., inside of a skate ramp, while everyone swings miniature wrecking balls at them, knocking them down. "The Wind Tunnel" is another funny skit where Bam Margera gets blown away from a huge wind propeller inside of a horse trailer, then the crew puts a king cobra inside and locks him in (Bam has a snake phobia, and, as predicted, flips out).
One of the more extreme skits is "Terror Taxi", where they dress up Ehren Mcghehey (spelling?) as a Middle-Eastern terrorist to play a prank on a taxi driver driving to the airport. Danger Ehren doesn't know that the driver is actually an actor hired to prank Ehren and the cameraman, and he pulls a fake gun on them both, puts Ehren in the trunk of the taxi, makes it sound like Bam Margera is shot, and drives the taxi around the parking lot.
Ehren is scared out of is wits and is crying, saying things like "Why did I agree to do this?" when the car stops and they surprise him, telling him it was all a huge prank on him. Ehren is happy until the crew drops another bombshell - the beard for his costume is made out of the crew's pubic hairs. Ehren pulls off his beard, and realizing he ate some of the hairs earlier, pukes everywhere.
The movie ends with a huge musical number, where the whole crew does stunts in a Broadway-type setting (I think the song is "The Best is Yet to Come"), and during the credits, it shows all of the outtakes with more stupid stuff (cameraman puking, Wee Man hides in a cooler and scares one of the guys in Three Six Mafia). The End.
That's all I can remember for now. I'll e-mail more if it comes to me of you can add on from other people, I don't care. All in all it was a good movie, just go in there with an open mind and a strong stomach.