I'd like to know where this unique phrase came from. “Orc and pie” has become shorthand for a style of simple dungeon design, but where did it originate?
Presenting Monte Cook’s "The Orc and the Pie", ©2001
The World's Shortest (Yet Technically Complete) Adventure: A Parody
"The Orc and the Pie"
Adventure Background: An orc has a pie.
Adventure Synopsis: The PCs kill the orc and take his pie.
Adventure Hook: The PCs are hungry for pie.
Room 1: The Orc's Pie Room
You see an orc with a pie.
The room is 10 feet by 10 feet.
Creature: An orc.
Treasure: A pie.
Concluding the Adventure: Pie tastes good.
Further Adventures: Somewhere, there is a bakery making these good pies. Perhaps it's guarded by more orcs.
WHAT DO YOU DO???
It was an example adventure by Monte Cook
It seems to have been made as an example adventure that is as short as possible while still being an actual adventure hook, but it is no longer available on their website. (Here's an entry for it on rpggeek.com, which puts its publication at 2002, and shows an image for it that dates it to 2001.)
The synopsis is basically:
There's an orc, he has a pie, the adventurers are hungry.
It has everything an adventure needs: An adversary, a MacGuffin the players need, and a reason to get it.
Somehow this caught on and more people started using "Orc & Pie" as a phrase to mean "extremely simplistic adventure." It essentially became a meme, which helped spread its name.
In fact, if Wil Wheaton is to be believed, it can also be used as an easy starting point for learning a new game system.
As others have already answered, “orc and pie” came from American game designer Monte Cook’s “The Orc and the Pie”—“The World's Shortest (Yet Technically Complete) Adventure: A Parody”.