My table likes to punctuate the horror of battle and often tragic developments of their backstory by adding in stupid things we can all have a giggle at. For example:

I'm running a campaign where in the first town a magic shop owner asked if the party wanted to sign up to hear about their new offers for a 10% discount. The party figured they wouldn't be there long so wouldn't have to put up with letters coming to the tavern more than once or twice. They also had  limited funds as low level players so they bit the vendors hand off.

Many sessions have since passed and every now and then, usually in tense moments, they will hear the voice of the vendor via the Sending spell updating them about "Wound-Free Wednesday's: Half off healing potions this Wednesday only. Whether your a guardsman, adventurer or just super clumsy head down to Ariadne's Arcana TODAYYYYYY! Offer available while stocks last."

It's a running gag for us now and even when I don't do it at tense moments one of the players will bring it up. What running jokes do you have at your table and for DM's what weird funny stuff to you do to add a bit of levity?

Three of my players have Sending and have postulated about how arcane shopkeeps should use it for telepathic junk mail. I am so happy to share your story with them, lol.

We have a few running gags:

Bedtime Check. The bard rolls athletics checks to jump into bed at the end of a long adventuring day, DC of 10 (his idea). When he fails, he misses and lands on the floor. He's got a losing record.

God Court. In my games, resurrection spells aren't guaranteed - you instead have a social encounter with a deity who happens to be watching or who has claimed your soul. A group skill challenge ensues, and the results determine how effective the resurrection is. Well, the first time this happened, the god who was watching was the God of Might and Order, and his encounter was structured like a trial, holy courtroom and all. My players immediately dubbed it "God Court" and treated it like a Judge Judy episode. "Don't make me go to God Court for you" is now a running joke in- and out of character, said to a person who has just done or proposed something stupidly dangerous.

Sneeze Save. My players think everything remotely dungeon-like is littered with traps, even museum tourist attractions. So when they make themselves paranoid for no reason, I occasionally have them roll a CON save and dramatically describe them doing something mundane, like sneezing.

Fantasy Treats. With a campaign that takes place in the Underdark and involves some horror and tragic motifs, I wanted to make sure there were fun and whimsical things available to keep things light. Enter the magical candy shop, with a proprietor on a perpetual sugar high and her pet blink dog. The sweets were a huge hit with the players, as was the discovery that ice cream is canon in my universe. 

Quote from theologyofbagels >>

Three of my players have Sending and have postulated about how arcane shopkeeps should use it for telepathic junk mail. I am so happy to share your story with them, lol.

We have a few running gags:

Bedtime Check. The bard rolls athletics checks to jump into bed at the end of a long adventuring day, DC of 10 (his idea). When he fails, he misses and lands on the floor. He's got a losing record.

God Court. In my games, resurrection spells aren't guaranteed - you instead have a social encounter with a deity who happens to be watching or who has claimed your soul. A group skill challenge ensues, and the results determine how effective the resurrection is. Well, the first time this happened, the god who was watching was the God of Might and Order, and his encounter was structured like a trial, holy courtroom and all. My players immediately dubbed it "God Court" and treated it like a Judge Judy episode. "Don't make me go to God Court for you" is now a running joke in- and out of character, said to a person who has just done or proposed something stupidly dangerous.

Sneeze Save. My players think everything remotely dungeon-like is littered with traps, even museum tourist attractions. So when they make themselves paranoid for no reason, I occasionally have them roll a CON save and dramatically describe them doing something mundane, like sneezing.

Fantasy Treats. With a campaign that takes place in the Underdark and involves some horror and tragic motifs, I wanted to make sure there were fun and whimsical things available to keep things light. Enter the magical candy shop, with a proprietor on a perpetual sugar high and her pet blink dog. The sweets were a huge hit with the players, as was the discovery that ice cream is canon in my universe. 

 

 Haha I love the God Court one in particular. How's its just become shorthand for that idea will get us all killed! 

A long while back in my current campaign, the party was in a town where everyone was touched by a bit of madness, and one of the NPCs exhibited his madness by playing childish pranks--pantsing the party members, putting their hands in hot water while they slept, putting a bucket of water over a door so it would splash them when the door was opened.   Silly things that really had no major consequences.

The party loved to hate the NPC, and as they ventured out of town, their characters kept discussing how they would come back to that town and punish the prankster one of these days once the world was not ending and they had some down time.  So, since they seemed to delight in the NPC harassing them, his handiwork has shown up in pretty much every town they go to.  Barstools that have been sawed halfway through so someone sits on them and falls.  Bottles of fine wine that have been carefully emptied, filled with vinegar or the like, and refilled.  Whoopie cushions.  Banana peals left underfoot.  It's all very silly, but they all get a kick out of it every time they fall for some kind of prank. 

Love this. It'd be hilarious if he somehow managed to become integral to the plot and the party had to protect eventhough he refused to give up on his nonsense!

My players befriended an ooze and mimic in what is now their home base. These creatures are also friendly to each other. 

So far they've created bowling. The ooze splits off and then the mimic spits out an ooze ball. 

The ooze got into some growth potions. 

Much more to come which I won't reveal case a player reads this. But they love the little things that the mimic and ooze get into. 

I introduced an insane alchemist into one of my campaigns that sold cursed potions (well, not cursed, more like unintended side effects).  They nicknamed him 'twitchy' and now he shows up in all the campaigns with that group.  I have fun creating new potions, and they have fun buying them and seeing what happens when they are used.

I ran an entire oneshot which was brimful of terrible puns and references for the players. The characters, however, would not even bat an eye at them!