Here's my latest theory: in order to make memorable D&D encounters, all you have to do is keep your eyes open for odd metaphors in fiction, and think "What would this be like if it were literally true?"
"I suppose the fellows will show fight."
"Not a doubt of it, from the specimen we have had of them. They know that they have no mercy to expect at our hands, and that they fight with ropes round their necks."
The Pirate of the Mediterranean: A Tale of the Sea (William Henry Giles Kingston)
Actual meaning: The fellows will be hanged if captured.
D&D meaning: The pirates of this sloop actually fight with nooses around their necks, with the strangle rope dangling behind them. This is to prevent them from running away: if they turn to flee, you can grab the noose and strangle them. As a side benefit, it freaks people out. As a side penalty, they're extremely vulnerable to flanking attacks.
Ask all mankind about both me and them,
When I attack on the day of battle.
I have left their lions overthrown in war,
Among those plains upon the burning ground.
-The Arabian Nights
Actual meaning: I'm not much of an interpreter of Arabian poetry, but I suppose the guy speaking has defeated some enemy warriors?
D&D meaning: WAR LIONS. What a great idea. One of my campaign world's empires now uses trained, armored war lions. They're too dangerous to ride: they're a terror weapon. It takes a brave front line to stand against a charge of fifty armored lions.
"Local folklore? How does it go?"
"You wouldn't be interested."
"I just said I was."
"Then you shouldn't be. It's old pig-wife talk."
-Greg Keyes: The Briar King
Actual meaning: It's gossip spread by the wives of pig farmers.
D&D Meaning: The Pig Wife is a woman who lives in the fey woods. She will apologize that her husband is not there to greet visitors, but he has unfortunately "escaped from his sty." If visitors stay for dinner, she will serve them pork chops. Anyone who eats a pork chop will be attacked within 24 hours by an enraged wereboar wearing a wedding ring.