Once, a friend created a character who was a gnome bard. He was supposed to be a great singer but in his backstory, every time he sang, small animals would run away in terror. It made for some hilarious role - playing moments when he tried to perform in taverns.
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.
Sure. Once, my friend's character, a bumbling wizard, tried to cast a spell to make himself fly. Instead, he turned his robes into a giant, flapping bird that carried him around while he flailed helplessly. It was hilarious.
One funny DnD story from 4chan was about a player who tried to use a 'confusion' spell on a group of goblins. Instead of getting confused, the goblins started doing a chaotic dance and singing a made - up song. It was hilarious as the whole encounter turned into a comical performance rather than a fight.
One time in a DND game, I rolled a Nat 1 when trying to pick a lock. Instead of quietly unlocking the chest, my character ended up jamming the lock so badly that it set off a trap. There was a puff of smoke and a small explosion that singed my character's eyebrows. It was hilarious because it completely derailed our plan to sneakily loot the treasure.
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.