The Sweetest Laugh

οὔκουν γέλως ἥδιστος εἰς ἐχθροὺς γελᾶν;
To laugh at enemies, is that not the sweetest laughter?

Sophocles Ajax 79.

Athena puts the question to Odysseus, but the Ithacan king refuses to embrace even a divinely endorsed schadenfreude.  One ought to admire Odysseus' restraint.  Other men have been less hesitant to rejoice in the misfortune of a rival, and most would gladly exact revenge themselves.

In Herodotus, Astyages' cannibalistic prank on Harpagus finds its recompense in the desertion of the Medes to Cyrus.  A great price to pay for a Thyestean Feast, though I think most people would judge Harpagus leniently. 

The menu for Achilles in his post-Patroclan world offers different fare.

Before then, for me at least, neither food nor drink
will travel down my throat, not with my friend dead,
there in my shelter, torn to shreds by the sharp bronze...
His feet turned to the door, stretched out for burial,
round him comrades mourning.
You talk of food?
I have no taste for food -- what I really crave
is slaughter and blood and the choking groans of men!

Homer, Iliad 19.209-214, (tr. Robert Fagles)

Delicious, but he'll just be hungry again in an hour.

Perhaps the example of William Poole is best.  He retaliates via the opposite orifice.

There was then William Poole, a nibbler at astrology, sometimes a gardener, an apparitor, a drawer of linen; as quoifs, handkerchiefs; a plaisterer and a bricklayer; he would brag many times he had been of seventeen professions; was very good company for drolling, as you yourself very well remember (most honoured Sir); he pretended to poetry; and that posterity may have a taste of it, you shall have here inserted two verses of his own making; the occasion of making them was thus. One Sir Thomas Jay, a Justice of the Peace in Rosemary-Lane, issued out his warrant for the apprehension of Poole, upon a pretended suggestion, that he was in company with some lewd people in a tavern, where a silver cup was lost, Anglice stolen. Poole, hearing of the warrant, packs up his little trunk of books, being all his library, and runs to Westminster; but hearing some months after that the Justice was dead and buried, he came and enquired where the grave was; and after the discharge of his belly upon the grave, left these two verses upon it, which he swore he made himself.

Here lieth buried Sir Thomas Jay, Knight,

Who being dead, I upon his grave did shite.

WILLIAM LILLY'S HISTORY OF HIS LIFE AND TIMES, FROM THE YEAR 1602 TO 1681

Maybe the real moral of this story is that the safest time for revenge is after one's foe has joined the majority.  It is impressive what six feet of earth can do for the bravery of a man.