It's a Saturday lunchtime one day in the early 1950s. Dad has finished his shift at the factory and rides his bike home faster than usual because he's promised little Jimmy, his seven-year-old son, that he'll take him to the big game between City, the local team, and United, their hated rivals.
(In the interests of impartiality, this joke is being related with two fictitious football teams. Readers should substitute their own favourite team for 'City', and insert the name of their least favourite team for 'United'.)
But when Dad and Jimmy get to the City ground, they find it's completely sold out. Jimmy is bitterly disappointed as he's been looking forward to seeing the match with his dad all week.
"Tell you what, lad" says Dad. "Let's go to the pictures instead. We'll go and see that new film Quo Vadis. You'll love it. It's a big epic, in colour, and it has Roman soldiers in."
So they go to see the film, and little Jimmy is watching quite happily until the scene of the Christians being eaten by the lions. Dad can see he finds this upsetting, so he whispers to him, "It's OK son, those are United supporters the lions are eating."
Jimmy brightens up considerably at this, but then only a few moments later, he starts to cry.
"What's the matter?" asks his Dad.
"There's two lions in the corner who aren't eating."
This gag has all the hallmarks of something cooked up on the terraces, or maybe some northern club circuit comedian, but it's unlikely to pre-date 1951. There had been at least three silent-era film versions of Quo Vadis, two Italian and one French, but it was the big Hollywood epic of 1951 that had the greatest impact. It starred Robert Taylor and Deborah Kerr, but the entire show was effortlessly stolen by Peter Ustinov hamming it up gloriously and setting the all-time standard for anyone trying to play the emperor Nero.
The film was based on the novel by Polish author Henryk Sienkiewicz (1846-1916), who won the Nobel Prize for literature in 1905. The title, Latin for "where are you going?" comes from the legend that as St Peter was fleeing Rome and certain death, he met Christ going in the opposite direction and asked him where he was going. "I am going to Rome to be crucified again" replied Jesus, thus giving Peter the courage to turn back and resume his mission.
Sienkiewicz researched his novel carefully and the story, of the love between the young Christian woman and an upper crust pagan Roman, includes a number of genuine historic characters and incidents.
But as experts keep telling us, there is no direct evidence that Christians were ever fed to lions in the arena. Under Nero, Christians were persecuted and killed in all sorts of horrible ways, but not eaten by lions as portrayed in the book and movies. Of course given the Roman mob's love of savage spectacle, it's almost certain that at some point and at some place in the empire, Christians were devoured by lions. But probably not in Rome in Nero's time.
Not that any of this will stop Christians being fed to lions continuing to be the stuff of both drama and jokes. Like the more recent one in which the Christians, faced with the lions, start praying: "Lord, please give these lions Christian souls!" At which point the lions stop, put their front paws together and are heard to say: "For what we are about to receive ... "