I remember when Steve, our Pastor, first proposed during a sermon that one of the more obscure parables (of course I can't remember which!) could only be understood if you realize that it might be a joke. It blew my mind because I'd never thought of it, and yet it made so much sense.
Here's Frederick Buechner (in 1973) on the same topic:
A parable is a small story with a large point. Most of the ones Jesus told have a kind of sad fun about them. The parables of the Crooked Judge (Luke 18:1-8), the Sleepy Friend (Luke 11:5-8), and the Distraught Father (Luke 11:11-13) are really jokes in their way, at least part of whose point seems to be that a silly question deserves a silly answer. In the Prodigal Son (Luke 15:11-32), the elder brother's pious pique when the returning Prodigal gets the red-carpet treatment is worthy of Moliere's Tartuffe, as is the outraged legalism of the Laborers in the Vineyard (Matthew 20:1-16) when Johnny-come-lately gets as big a slice of the worm as the early bird. The point of the Unjust Steward is that it's better to be a resourceful rascal than a saintly schlemiel (Luke 16:1-8); and of the Talents that, spiritually speaking, playing the market will get you further than playing it safe (Matthew 25:14-30).
Both the sadness and the fun are at their richest, however, in the parable of the Great Banquet (Luke 14:16-24). The "beautiful people" all send in their excuses, of course-their real estate, their livestock, their sex lives-so the host sends his social secretary out into the streets to bring in the poor, the maimed, the blind, the lame.
The string ensemble strikes up the overture to The Bartered Bride, the champagne glasses are filled, the cold pheasant is passed round, and there they sit by candlelight with their white canes and their empty sleeves, their orthopedic shoes, their sleazy clothes, their aluminum walkers. A woman with a harelip proposes a toast. An old man with the face of Lear on the heath and a party hat does his best to rise to his feet. A deaf-mute thinks people are starting to go home and pushes back from the table. Rose petals float in the finger bowls. The strings shift into the Liebestod.
With parables and jokes both, if you've got to have them explained, don't bother.
~originally published in Wishful Thinking and later in Beyond Words