AVGN: Front door, closet... front door, closet... closet.
In the Angry Nerd Christmas Carol, old man AVGN insists on playing the motion controlled rhythm game Boogie and making needlessly grandiose gestures despite being not physically fit to do so. He even persists while having a heart attack, and you can imagine how that ends.
Danbooru has two pools dedicated to this trope. First of all the "Digging Your Own Grave" pool, which is about characters doing/saying something stupid with a lack of foresight and being about to be punished for it, comments along the lines of "Death Flag triggered" are quite common. Secondly is the "Told You Not To Do That" pool, which is about the aftermath and/or consequences of characters doing/saying something stupid with a lack of foresight.
Cracked blog once poked fun at Terminator, specifically how all these people were clearly either terminally dumb or seriously determined to self-terminate (sorry). That is —
Cyberdine's tech support engineer: ...Again, my strength really lie in fixing computers, not in designing or managing needlessly nightmarish robots, but it just seems like a basic rule of computer-making that you should be able to turn it off at some point. I mean, my toaster has a plug in case something goes wrong, you know? And i haven't armed my toaster or given it access to my house's security system.
Eli from Deagle Nation classifies as this — he once tried to "parkour" over his mom's table, which ends up netting him a trip to the hospital.
Misa: Okay guys it looks like you have everything you need so I'm gonna go to bed now! Alone! Naked! And with the door unlocked! Bye!
The Demented Cartoon Movie has a driver who crashes his car into a wall at full speed after reacting indecisively to his onboard computer warning about just that.
"I think you should steer. Do you want to crash?" "Uhhhhhhhh..."
From the Dragon Ball Z Abridged Movie The World's Strongest(pre-Team Four Star): Doctors Wheelo and Kochin have just discovered that Gohan has an infinite supply of badassery and ki that only comes out when he is pissed.
Wheelo: Kochin, did you feel the amount of energy that just came out of him?
Kochin: Yes, I did. And I have a great idea! Let's piss him off until he explodes!
On the Team Four Star version of Worlds Strongest, Kochin still wants to piss Gohan off because of his power while Wheelo(who isn't evil in this version) knows how bad it is to piss off someone with lots of power.
For a single episode example, in "Chew Said a Mouthful" Nutty gets a jawbreaker and doesn't understand the basic concept of how to eat it or why it has its name, so his attempts to chew it lead to his mouth getting wired shut, then at the end of the episode he tries to chew it again and dies.
In the episode "All Work and No Play", Nutty, Sniffles and Lammy all get maimed by playing on a clearly unsafe old playground that Lumpy was in the middle of demolishing, though it's thanks to Lumpy that Nutty and Sniffles are both killed.
While in his emo phase, IGSRJ consumes an entire bottle of whiskey, drives 60 MPH through a residential neighborhood, and plays Duke Nukem Mobile on his cellphone. He manages to get through WITHOUT INCIDENT!
Played for laughs in his Nintendo Sticker Album review, where he decides to stick a fork in an electrical socket to literallyplay with power.
Pretty much the entirety of Klay World is this trope. Throughout the entire series the population of Klay World, the klaymen's, have gotten themselves in scenarios that would most likely result in their death.
J from Marble Hornets has made such brilliant decisions as, after being attacked when he visited an abandoned house, immediately deciding to return. Then announcing when he would do so to the internet at large. Totheark, who J thinks is the attacker, responds with a video that basically amounts to, "Yes, please come so we can eat you!" J still goes. At night.
And taken to new heights in Entry #40, wherein J gets tired of waiting for Alex, so he decides the best idea is to go for a walk in the creepy haunted woods. He had never been in the woods before, didn't know his way around, and, needless to say, didn't tell anyone where he was. On the plus side, he then did the most sensible thing anyone in the whole series has done so far: When Slender Man shows up to say hi, J just drops the camera and runs.
The Interviewer guy of On the Set of 4th Edition normally is a Cosmic Plaything, getting killed by the creatures he interviews that don't get killed alongside him. But when drunk, all survival instincts flee him at high velocity as, to demonstrate a skill challenge, he decides to hit on The Lady of Pain, who he knows is capable of nullifying gods and flaying people with a glance, and he outright tries to intimidate her into giving him her number. Of all the times he's been killed in these shows, this was the one time he deserved it.
About 99% of the people in the trailer in the fake Shark Pool movie. A giant, man eating shark has somehow ended up in a swimming pool...and yet they don't just stay out of the pool...which the Only Sane Man repeatedly suggests they do.
Shrooms has Red; he believes the right way to drive ghosts from a haunted house is to insult their originality.
February, the schience officer from Starship who goes down to an uncharted alien planet and scans the air for breathability... after taking off her helmet. It gets worse from there.
Bowser Junior from Super Mario Logan, to the extreme. See what he's doing on the page image? He's putting his tongue on the blades of Cody's drone. Even when Cody told him not to. Bloody Hilarious results ensue.
Crops up from time to time in Survival of the Fittest. One of the most notable examples was the very first death in v4. Danya tooks pains to tell the students that the collars were more sensitive this time, and not as prone to tampering. This does not stop Remi Pierce from attempting to slice off his collar with a knife the second he woke up on the island, with expected results.
Team Service Announcement: The BLU Heavy in Minigun Spinup takes so long to walk anywhere with his revving Brass Beast that the RED Spy and Sniper decide assassinating him is just too easy to be fun. So instead they drive a steamroller over him.
The BLU Soldier in Grenade Launcher willingly stands on a stickybomb trap, claiming "I got a good feeling about this!"
Third Rate Gamer has a bomb lying around in his house for no good reason. As if that weren't stupid enough, he sets a game on fire and manages to throw it at the bomb, lighting the fuse.
Many a video gameCreepypasta protagonist turns out to be this, insisting on playing clearly broken copies of the game (usually without labels and the title written in Sharpie,) and even when the game doesn't force them to keep playing via supernatural means, they'll keep playing even when the sinister parts of the game reveal themselves.
Some go the extra mile, like the protagonist of "Blood Whistle", who becomes convinced that he has to beat the game and then kill himself after all the horror that he's witnessed (he comes to this decision on Stage 2, when he could've easily just bailed out.) Even when people on the fake forum he's posting his recounting of what's going on to manage to get campus police on his case, he just sends them away and then bans the culprits before continuing with the game (and when he does finally go through with it, he opts to go with the overly-complicated method of somehow impaling himself on a recorder.) Keep in mind that the game was not directly controlling him to do any of this; He decided to do it all on his own.
Inverted in Ultra Fast Pony, where Rainbow Dash is literally too dumb to die.
Multiple player characters in The Binder of Shame. "Everyone agreed there should have been some sign that the Desert of Certain Doom might be dangerous."