Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is the fourth movie in the hit gross-out comedy franchise based on a TV show that aired from 2000-2007. I'm pretty sure the TV show "Ow My Balls!" in the movie Idiocracy was based on it. If you're a fan of testicular trauma, then these guys are for you. They go to great lengths to try to destroy the family jewels. But there's also a lot of other non-testicular gross-out comedy, including booby traps, exploding toilets, exploding chairs, a human bike ramp, a shirtless guy falling in cactus, lighting farts underwater, covering a guy's genitals with bees, and all sorts of other mayhem. There are even a couple of scenes that traumatize people with snakes.
In the first snake scene, the head ball-crusher Johnny Knoxville tells some guys that he will try to take a cookie off a rattlesnake's head. Jules the snake handler then removes a Western Diamond-backed Rattlesnake and puts it on the floor to show them what they will be facing in the room after the lights are turned out, telling them that the snake will kill them if they get too close. But we are in on the joke when we see the movie crew tells him to take the snake out of the room before the stunt begins. Then we see the dark room through night vision as they play snake sounds and Knoxville fakes the guys out with a large rubber snake. It looks silly from our perspective, but the guys seem genuinely terrified, because they know that Jackass does not usually pull any punches.
In the second snake scene we see three people dressed as mimes each given a challenge. Because mimes should always be silent, if they make a sound during their challenge they lose. The first mime has to stick her tongue into an electric charge. The second has a skateboard fall on his feet like a guillotine. The third mime, Poopies, is told he will have to kiss a deadly viper. Someone asks what kind of snake it is and the snake handler Jules tells them it's a Texas rat snake. (The species is actually not venomous or dangerous, but it is known for its angry disposition and its penchant for biting - which I can confirm.) The mime assumes the position in front of the snake and is then bitten on the face a couple of times. We can see blood on his lips and nose, but since he never made a sound when the snake was biting, he wins.