Gaming story:
I'm running Phandelver. So, they blew into town, I introduced a bunch of NPC's, and not a single one of them stuck. Nothing. The players didn't really care about any of them. A few sessions later, they head to Neverwinter to do some stuff, and on the way back to Phandelin, I drop in a random one shot adventure: A Tough Tavern to Swallow. Nothing too serious, I just wanted to run it.
When the party walks into the bar, the lizardfolk bartender says, and this is a direct quote from the boxed text: "Hey Ned. Your face is long. You are a horse." in an attempt at telling a joke.
The party latched onto this NPC like a freaking limpet. I actually had to transport the NPC to Phandalin (becoming the new bartender at The Sleeping Giant). They have never again set foot in the actual inn in town where the adventure assumes the party will hang out.
I spent time making images, backstories, connections for all these Phandalin natives, and watched it all swirl down the drain because the party loved a stupid joke. For a one shot NPC that I had not done single thing for.
Sometimes I hate players.