These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
In the DVD commentary of Jackass: The Movie, Johnny Knoxville makes fun of Ryan Dunn's poor driving skills.
Any car/vehicle stunts Ryan Dunn participated in.
The "Son of Jackass" scene at the end, which is meant to depict the cast — including Dunn — as eighty-year-old men.
In the season one DVD's commentary, an obviously drunk Steve-O jokes, "Hey guys, I think I might be drunk, I better go to rehab." Steve-O eventually ended up actually going to rehab to deal with his alcoholism (among other substance abuse problems).
Guilty Pleasure: The show is basically 30 minutes of guys hurting themselves for our, and their own, entertainment.
Practically any time Chris and Steve-O are together some Ho Yay is bound to happen, but especially in the Gumball 3000 episode (where they were stuck in the backseat together for five days and passed their time with such activities as "Jaguar Gymnastics," AKA them climbing on each other half-naked). Ho Yay was also a staple of the humor on Wildboyz, and at one point on the show they even kissed (of course, afterwards, Chris immediately claims that they didn't really mean to kiss, and Steve-O leans over the side of the boat to rinse his mouth out).
Even more so behind the scenes. It's never mentioned in the episode itself, but in the DVD commentary and in interviews, Chris and Steve-O mention that they spent much of the Gumball trip jacking off together, even making a competition out of it.
An interview on the old Jackass World website had Chris reveal that on the Wildboyz Russia trip, him and Steve-O were both very drunk on a bus ride, and Steve-O thought it would be a fantastic idea for a "stunt" to kiss Chris's dick...and then actually did it. Unsurprisingly, it never actually made it into the show.
Jumping Off the Slippery Slope: Steve-O had always had substance abuse problems, but the other cast members always let it slide (in part because they all were also drinkers and drug users, and, despite never using them the way he did and certainly not having the same addiction problems as him, felt they weren't in the place to criticize him). It really became a problem after the second movie, especially in late 2007 and early 2008, culminating in him being such a bitch to work with during the MTV 24-hour takeover that Jeff Tremaine finally decided to just completely kick him out. Thankfully, shortly after that they staged an intervention for him, sent him to the mental hospital and later, rehab, and ever since he's been completely sober and arguably the most pleasant out of all of the cast.
Some believe Bam is going through this. Shortly after Dunn's death, his marriage with his childhood sweetheart, Missy (which he and MTV made an entire TV show about his wedding), collapsed and he ended up having three affairs. He and Missy then got divorced and got married with another woman later on. The incident, as well as him talking about it like winning a prize on The Howard Stern Show didn't help, resulting with him loosing fans.
Moral Event Horizon: The Beehive Limo Bait and Switch prank in the second movie may have been going too far, especially if one of the cast members had an unknown allergy to bees.
Nausea Fuel: Considering the point of the show, it's to be expected, but...
Hands-down, the most disgusting one ever was the tail end of the horse scene in Jackass Number Two — a scene so bad that it made a crew member vomit on set. Chris Pontius drinks horse semen. It was even blurred out in the theatrical version. There, now do you still wish you wanted to know that?
Jackass 2.5 reveals they also splashed it on a cameraman. The container was washed out and replaced with water, mind you, but it still disgusted the rest of the crew.
Dave England shits on a toy house toilet, gets the same reaction of disgust. The cameraman dry retches rather painfully.
The poo volcano in Jackass 3D, which is about as shitty as it sounds.
The climax of Jackass 3D — Steve-O is strapped into a porta-potty filled with all kinds of shit (literally) and flung high into the air. The cameras get covered in shit, there's a shit shower, it was so disgusting that nearly everyone puked..
The Sweatsuit Cocktail. Preston works out vigorously while wrapped in plastic wrap, and his resulting sweat (taken lovingly from his crotch and ass crack) is funneled into a cup. Which Steve-O then drinks. Remember Lance Bangs, the man who vomited during England's poop-encrusted adventures with a hardware store, a dollhouse, and during the horse scene? This scene causes Lance to throw up on his own camera.
England eats the ingredients of an omelet, then proceeds to vomit it back up. He then takes said vomit and cooks an omelet, which he eats. During the segment, Johnny Knoxville wears a Hazmat Suit. It's for humor value, but you kind of get where he's coming from.
Noodle Incident: An interesting example in the box set's commentary. All of the cast members repeatedly make jokes about horse cum, but explain nothing other than that it's a scene that was filmed for Wildboyz but never made it into the show. Bam even lampshades the trope by pointing out that no one watching will understand why horse cum is supposed to be funny. However, it stopped being a Noodle Incident a year later when the scene was included in Jackass 2 - Chris "milking" a horse and then drinking the cum.