One funny DnD story I heard on Tumblr was about a player who tried to charm a dragon. Instead of getting charmed, the dragon just looked at the player and said, 'You think that works on me?' and then ate a nearby sheep to show how unimpressed it was.
Well, there's a story where a rogue thought he could steal from a powerful mage. He snuck into the mage's tower and started rummaging through things. But the mage had set up all kinds of magical traps. The rogue ended up with his pants on fire and his hair turned bright pink. It was a total disaster for him but so funny for the rest of the party.
Once, my character, a clumsy wizard, was trying to cast a simple light spell in a dark dungeon. Instead of just a small orb of light, he made a huge explosion of blinding light that not only illuminated the whole area but also scared the rats so much they ran right into the goblin guards, causing total chaos.
Once, our party's bard tried to charm a dragon with his music. He started playing this really wild tune. The dragon just looked at him like he was crazy for a moment, then started to sway along as if it was enjoying the show. It was hilarious seeing this huge, terrifying dragon getting into the music instead of attacking us right away.
One funny paladin DND story is about a paladin who was so dedicated to his code of honor that he accidentally challenged a very old and cranky tree spirit to a duel. The tree spirit was just sitting there, minding its own business, but the paladin misinterpreted some rustling of the leaves as a threat. The duel consisted of the paladin trying to swing his sword at the branches while the tree spirit just dropped acorns on his head. It was hilarious to see the paladin getting so frustrated.
During a DND campaign, my character rolled a Nat 1 for a stealth check. I was trying to sneak past a group of guards. Instead of being quiet, my character tripped over their own feet and made a huge racket. The guards immediately noticed and started chasing me. My friends' characters had to quickly come up with a plan to either fight the guards or create a distraction so I could get away. It was so funny because it was supposed to be a simple sneaking mission but turned into a chaotic chase scene all because of that Nat 1.
In a DND campaign, a bard entered a tavern and challenged the local drunk to a singing duel. The drunk accepted, thinking it would be easy. But the bard started using all kinds of magical enhancements to his voice and performance. He made his voice echo like there were multiple bards singing, and he added illusions of dancing animals. The drunk was so flabbergasted that he passed out from shock, and the bard won the duel and free drinks for the whole night.
One popular type of funny story post on Tumblr is the 'awkward encounter' story. For example, stories about meeting an ex in a really strange situation. Another popular one is the 'funny pet story', like when a cat does something completely unexpected. There are also those 'funny school or work' stories that many can relate to.
A funny fake Tumblr story I remember is that there was a so - called 'invisible friend' living in someone's attic. According to the story, this friend would move things around and play pranks on the family. They would find their keys in the fridge or their shoes on the ceiling fan. Another story was about a person who claimed their toaster was possessed and would only toast bread into the shape of famous landmarks. One more story was about a cloud that followed a particular person everywhere and would rain on them when they were sad.
One characteristic is the unexpectedness. Like in a story where a person thinks they are going to a normal job interview but it turns out to be for a job as a clown in a circus. The sudden twist makes it funny.