Perhaps you have heard of the 'Rule of Three' in comedy writing. For those that haven't, I point you to a really down-and-dirty quick definition/explantion by John Kinde:
"The first two items in the triplet set the pattern (the "straight" line) and the
third item breaks the pattern (the curve/the twist/the derailment). Breaking the
pattern heightens the tension and creates the surprise, usually resulting in
He's got a more detailed explanation here.
But I've found that it's always good to have masterful examples - all the better to illustrate. And who could be better or teach more about the rule of three than Terry Pratchett? His books are riddled with countless examples.
In Going Postal, Pratchett opens with a "The Nine-Thousand-Year Prologue." He describes ships and wreckage floating on rivers beneath the ocean's surface - which is quite whimsical to begin with.
Then you come across this line: "Some stricken ships have rigging; some even have sails. Many still have crew, tangled in the rigging or lashed to the wheel."
(Yes, the 'ew' factor makes it funny too.)
But you have set-up: "Some stricken ships have rigging;"
You have the continuing line : "some even have sails"
You have the derailment: "Many still have crew, tangled in the rigging or lashed to the wheel."
That's on the second page.
Also in Going Postal:
The scene - Moist is about to be hanged in front of a large crowd. Pratchett tells us: "There was a stir when they climbed up into the chilly morning air, followed by a few boos and even some applause."
Set-up: "People were strange like that."
The continuing line: "Steal five dollars and you were a petty thief."
The derailment: "Steal thousands of dollars and you were either a government or a hero."
Your assignment, should you choose to accept it, is to write your own funny 'triplet.' You can have a second or two to set your stage, but after that we've gotta be able to see the set up, the continuing line, and then surprise us with your derailment.