Often, there is a role reversal in funny ends. Like in a story where the hunter becomes the hunted. Maybe the hunter who has been chasing an animal all through the story ends up getting chased by a group of angry squirrels at the end. This kind of role change can create a lot of humor.
Well, there's a story where a magician is trying to perform a disappearing act on stage. But instead of disappearing, he just gets his pants stuck in a trapdoor and has to hop around the stage trying to free himself while the audience laughs hysterically. That's a great funny end.
I don't think it's strictly true. It's probably a fictional story that incorporates some common themes and experiences to make it feel relatable and engaging.
In theory, it's highly unlikely to have a story that truly never ends. All stories have a natural conclusion or a point where they stop being relevant or engaging.