I'm pretty new to playing D&D, but just had my first "Critical Role-ish" level of epic gameplay. It was fun as hell, but for us, completely born out of a decision so utterly idiotic and bereft of common sense, that the outcome had no business being as amazing as it was. So that got me thinking of how many other stories are out there of people make colossally stupid in-game decisions, only to have it turn out incredibly well?

For us, my newly minted Conquest Paladin and fellow band of level 3 adventurers, fresh off of our triumphant battle against a horde of twig blights (to give some flavor of the caliber of threats were accustomed to experiencing), decided to take on a random quest in town. This one started out simple - to intimidate a rival competitor of the local town blacksmith, who the blacksmith accused of being a vampire even through the rest of the town widely knew this claim to be false.

So we ventured to competitor's home, decked out in a clear gothic motif, and after a couple of Eyes of the Grave & Divine Senses for good measure, confirmed that this rival was in fact, not a vampire. He only really liked gothic stylings. After returning to the blacksmith, who refused to pay us for our time, we dragged him to the rival's home to prove his folly once and for all. I and a single team mate were invited inside and led up to the rival's main chamber, a well lit room, with ample sunlight shining through the floor to ceiling windows. We confessed to the rival the reason for our visit, and after much exasperation, the rival shared his frustration with the continued abuse at the hands of the local blacksmith. As we chatted with the rival, the DM started dropping overt comments. Things like "yes he's very friendly, but he LOOKS like a vampire", and "I feel bad for him too, but did I mention that he REALLY looks like a vampire".  As we were led out of the chamber, only after buying two swords from the rival, I randomly decided to turn and douse him with holy water as final proof point for the blacksmith..****y to hear the sound of sizzling and burning skin.

As the room's illusion faded leaving us in a pitch black chamber (and me as a human with no darkvision), the DM just facepalmed and shook his head as we exclaimed "Wait, he really IS a VAMPIRE? Oh sh*t!".

At this point, my partner and I were left with two apparently equally impossible decisions...

 Of course, we chose..."we got this!". As my partner ran to find the other party members, I squared to take on the Vampire (CR 13, XP 10,000). Alone. In the dark. The party did arrive in time, but if the sheer stupidity of our (my) decision wasn't obvious enough out of the gate, it should have been made clear when on it's first bite of its first successful attack, it outright killed our Warlock (with our DM shaking his head the entire time). Of course, we responded in true Monty Python fashion ("T'is but a flesh wound!"). Yet over the course many rounds, something strange happened. With the help a few strategically placed smites, Protection Against Evil and Good spells, and copious amounts of luck...we didn't actually die. Well that's not true, three of our party did. But we miraculously didn't TPK and actually defeated the Vampire on a last ditch smite/firebreath/silver arrow 1-2-3 combo. 

After revivifying our fallen members at the local cleric (using funds from the coffers of the Vampire), our DM was in such utter surprise that he actually had to end the session early because he hadn't yet fully planned out what to do in this case, since "no one in their right mind should have thought to do what we decided to do".

In any case, I'm sure that I did not do the session justice in my retelling here, but I hope that it ends up being a good read and inspires others to share their stories, because I would love to hear if others had similar experiences of epic fails turned into epic stories.

I had a similar vampire run in but it wasn't a PHB vampire, it was level approriate for 3. Sort of. 

My rogue while looking around town, sees a woman being attacked in an alleyway by a vampire. I shoot it to distract it, and then successfully hide behind a crate or soemthing. The woman escapes, I've lost the vampire. 

But that voice in the back of my head is thinking 'you could probably kill this vampire with a good sneak attack...

Turns out I could not, but the party cleric arrived and finished it off, saving my rogue who by then was put to sleep magically, but hadn't been killed/bitten yet .

----

A little while later, we snuck into a den of these lesser, level approriate vampires at like level 4 or so. And we had a plan to draw them into a room through a choke point. There were about 3 or 4 of them total I think. 

Then one of them cast fireball into our would be killing chamber and we panicked and fled the base. The vampires chased us, cue yackity sax music. Eventually as we ran, my character got caught up in something and one of the vampirse caught up and the barbarian attacked it. We very quickly realized these caster vampires were actually not as strong as we'd assumed based on melee centric vampirse we'd fought before, turned around and OBLITERATED them. 

When we reported in after clearing out the vampire den we left the chase part of the story out lol. 

My players found a pebble named it tiny rock tim and killed a siege tower with it

Party of 2 level 12 characters (my moon druid and an ancients paladin, I think?). Homebrew very powerful elemental amalgamation creature made of pure elemental energy. Meant to be a major fight.

Geas.

He became my pet.

so me and my party where on a ship sailing towards a city we needed to get to for a part of our quest, on our way their we found an otter who was acting very nervous, everyone decided to rescue it and bring it back onto the ship.

I'll spare you the details but basically we managed to get it back onto the ship. Anyway, once we did, we saw three orcas in the distance who were coming towards the ship, everyone decided they wanted to fight the orcas, one tried to talk to them but that got no where, one shot and arrow at an orca (if my memory serves me right) and one tried to use a spell which would kill the orcas but also kill all of us in the process (it had something to do with making a tsunami or something related to that). I was the only one who had peiced together that the orcas might be after the otter, so i yeeted the otter at the orcas which was a huge gamble because i may have just sacrificed an otter and the orcas would still attack.

To our shock, once the orcas ate the otter, they swam away and we were saved.

I then had a fight with the ranger of the group about how we shouldn't have killed the otter (something about how it isn't natural and survival of the fittest), i won the arguement.

I'm DMing an Icewind Dale:Rime of the Frodtmaiden game and whenever I would roll a random encounter table as they traveled I would roll orcs. The tabaxi rogue decided to give a communist speech to the orcs and convert them to Marxists. It worked every time.. now a majority of the orcs in the Dale are communist.

Later when the rogue and human monk were running against eachother to be speaker of Good Mead, the tabaxi won by also promising communism to the people... 

This rogue is going to turn the entire Far North communist unless i stop him... and I won't because I want to see how this plays out 

way back in 1e I was part of a party of 8 L20 characters in the demonweb pits. we came across Lolth and decided to attack (you really can't get stupider than to attack a diety in their home plane). Following the most ridiculous run of luck (10 critical rolls in a row on a called shot to the eye) Lolth was dead and  one member of the party became a god and resurrected the others.