[-[[caption-width-right:151:"That's not a running gag! That's a pun!" "[[VisualPun It's a running gag now.]]"]]-]
A joke whose humor derives from repetition, ideally becoming funnier each time it is repeated. ''Must'' be repeated at least [[RuleOfThree three times]], otherwise it's a BrickJoke. But repeat it ''too'' many times and it can become an OverlyLongGag. A variant is a joke that occurs OnceAnEpisode; doing ''that'' too often threatens to turn it into an OverusedRunningGag.
The ultimate fear for the use of any running gag is that it becomes an OverlyLongGag, or worse, that it was never funny in the first place and didn't improve through repetition. Nothing is worse than starting a one hour show with a joke that bombs that you're going to use twenty times over the next hour.
A '''Running Gag''' can be limited to a particular episode or recur throughout an entire series. If it recurs throughout an entire series, then it will often develop variations and/or be accompanied by LampshadeHanging. If a character [[BreakingTheFourthWall breaks the fourth wall]] to mention it, it's DidntWeUseThisJokeAlready. When the story goes on to kill off the gag for good (either with a final payoff or just by referencing that it's become ''too'' overused and it's ending right then), that is RunningGagged.
A comedy CatchPhrase is a type of Running Gag. Can become potential for MemeticMutation if the gag itself is widely applicable. Compare ArcWords, which are a recurring phrase that isn't a gag. See subtropes OncePerEpisode and EveryEpisodeEnding.
->-- [[Webcomic/OneOverZero The Running Gag]]