Noun
running gag (plural running gags)
An ongoing joke, one that is regularly repeated or continued.
Synonym: running joke
The running gag of the Grand Prix series is that whereas Murray [Walker], safe in the commentary box, sounds like a blindfolded man riding a unicycle on the rim of the pit of doom, the men actually facing the danger are all so taciturn that you might as well try interviewing the cars themselves. Clive James