Class Clowns: What is Funny and What is Dumb? 20/20" continues with teen kfl confidential. There has never been a shortage of stupid teen tricks, and they are going even further. So, here is dan harris with this year's crop of class clowns. Reporter: School is out for the summer and the internet is primed and pumping with adolescent idiocy on steroids. These days, the stupid teen tricks are more outrageous than ever. Digital age teen jack-assery even has its own vernacular -- planking. The cinnamon challenge. And eyeball shots with tabasco sauce and vodka. But those stunts are now hopelessly passe. Here's the new thing. It involves salt, a few cubes of ice and voila -- third degree burns! Reporter: Whoever can stand it the longest wins. Oh my gosh. It's a condom. Reporter: Think you've had the sex talk with your teen? Well you probably never imagined you would have to tell them where not to put a condom -- condom snorting is one of the hottest teen trends online right now. I'm going to be doing a challenge that I probably shouldn't be doing but that's okay. Did you hear that? Reporter: Yeah. I probably shouldn't be doing this, yet-- Reporter: She knows. Reporter: We're going to stop the video here because this is pretty gross, but that condom goes up her nose and comes out her mouth. I know what it means to be a teen in trouble. Reporter: Josh shipp is a behavior expert who has appeared on the reality show "teen trouble." There's actually a lot of dangers with the condom challenge. They can get caught. You can suffocate on it. Reporter: If they're not inhaling latex -- They might be inhaling alcohol. Smoking this type of stuff, does that actually do anything to you? This guy's claiming that he can get a buzz off of it. Reporter: Not just a buzz but oh, dude. Reporter: Not just a buzz but rapid intox case, because the alcohol vapors bypass the stomach and heads straight to a teenager's brain. A brain that is, by the way, already at a disadvantage. Is this an illustration of the fact that the part of a teenager's brain that regutes stupid impulses is not physically fully developed yet? This is a phase in their life where they are the most impulsive. They're thinking, you know, "will this be funny? Will people think this is cool? Reporter: Something else thenning and it isn't a new trend at all. A study out just this week shows teen speeding is on the rise. 18 year-old pranjal dahiya raced down this dark road at 110 miles an hour. Oh, jesus, take the wheel! Reporter: His friend was driving. Pranjal was filming. When you were speeding along, did you think, "this is pretty funny"? It was more like, "yeah, this is sweet." Like, "yeah, we're cool. night." I think some teens think that they're, like, one video away from becoming a celebrity. They want to be known. They want that attention. Hope you all enjoyed that. Reporter: Daniel jensen, an 18-year-old from california, gets lots of online attention because of high jginnings like this. His latest stunt was inspired by this nike video with kobe bryant. It popped up in my head and i was like you know what I think i want to try jumping over a car. Reporter: But a parked car wasn't enough -- daniel was set on one that was speeding towards him. Perhaps the only person with less common sense than daniel was the driver. My biggest concern was how he would know when exactly to jump. And he told me don't worry about it. I was supposed to have her drive towards me, about 40 miles an hour. And by the time I came down, she would be gone, so I wouldn't land on the car. But I jumped too late. I felt myself in the air. I closed my eyes and the first thought that went through my head was -- oh, my goodness, I just killed daniel. I just threw my feet down. And I was like "did I land that? I didn't die? Reporter: Daniel posted his video on youtube just two weeks ago and it has already impressed hundreds of thousands of viewers, but not his father. He made me promise not to do anymore stupid things. But we have different opinions of stupid. Reporter: Is there any risk that by showing these videos that we're encouraging people to do this kind of moronic stuff? We cannot protect our kids from seeing these sorts of videos. This is an opportunity for you to talk to your kid about them Reporter: And this part is key. He says, you have to talk in a certain way to be effective. Here's the idea. Lecturing leading to them tuning you out. But questioning leads to critical thinking. Reporter: Do you think this is dumb? Right, instead of saying, this is the stupid, do you think this is stupid? But furthermore, you need to show them what the possible dangers are. Find a video where it goes terribly wrong and show at video. Reporter: This is that video. Remember pranjal? As he recorded his friend speeding at 110 miles per hour the car hit a curve. I heard, like, the car screech. And then i, like, flew out the back. My entire body was numb. I broke my c-6 vertebrae. And then when it broke it, like, shattered, that paralyzed me from my neck down. Reporter: He has spent the last year recovering and adjusting to a life that will now be lived in a wheelchair. All this because of -- like, maybe 45 seconds of being stupid. Reporter: Which will be with you forever. Forever pretty much, yeah. Reporter: What's your message to kids? You can definitely have, fun, but there's always that limit, and don't, like, push it, push it, push it. Reporter: Do you point to your legs and said, "this can happ to you?" Yeah, I mean, I was that kid. Like, it's not going to happen