...or a story. This is how jokes work: you introduce a concept that's a bit off-centre: "Waiter, bring me a crocodile sandwich!" Then, when people are smiling a little at the oddness of this, you turn it around and twist it again: "And make it snappy!" Like a moebius strip, so it's turning in on itself and going around and around.
Here's another: "How many Freudians does it take to change a lightbulb?" Odd thought: a bunch of bearded and bespectacled psychoanalists clustered around changing the lightbulb. "Two, one to screw in the lightbulb, the other to hold the penis - I mean, ladder." Lightbulb jokes always rely on odd electricians: "...surrealists?" "A fish!" "...feminists?" "Do you think that's funny?"
All jokes use this basic formula. Shaggy-dog jokes just stretch out the first part for a loooong time. My old chief sub Jim Carwood used to tell one that involved a man leaving his house, bumping into a lamppost, making an insurance claim, putting the money on a scratchcard, winning a million, going into a pub, being picked up by an incredibly beautiful Indian woman, taking her home and going to bed with her and in the morning waking up and saying "You've got a spot on your forehead and scratching it - and he won another million! And the punchline: she says to him, "You're a lucky man!"
Stories use the same basic idea: your hero is put into a situation where he's thrown off centre - as in Claire Keegan's superb Foster, where the child of an all-over-the-place family is brought to stay for the summer with her mother's sister and brother-in-law. Then further off course: in Foster, the child's father drives off with her case of clothes, and the aunt and uncle dress her in boy's clothes and put her to sleep in a boy's room, but there's no boy in the house. Gradually, as the story opens out, things get odder, and yet reveal themselves, until with the twist at the end, in the last line - but I won't spoil the pleasure of reading it for you.
Lucille Redmond's ebook, Love, gripping dark and funny stories of love and revolution, is available on Amazon and iTunes