Hitchhiker's Guide to the Galaxy
Several paragraphs from the Infocom "Hitchhiker's Guide to the Galaxy" text-adventure that detail the player's use of unknown commands sparking an interstellar war, the full text of which follows. (Feel free to submit your favorite meme in place of "NO U".)
"It is of course well known that careless talk costs lives, but the full scale of the problem is not always appreciated. For instance, at the exact moment you said "NO U" a freak wormhole opened in the fabric of the space-time continuum and carried your words far far back in time across almost infinite reaches of space to a distant galaxy where strange and warlike beings were poised on the brink of frightful interstellar battle.
The two opposing leaders were meeting for the last time. A dreadful silence fell across the conference table as the commander of the Vl'Hurgs, resplendent in his black jeweled battle shorts, gazed levelly at the G'Gugvunt leader squatting opposite him in a cloud of green, sweet-smelling steam. As a million sleek and horribly beweaponed star cruisers poised to unleash electric death at his single word of command, the Vl'Hurg challenged his vile enemy to take back what it had said about his mother.
The creature stirred in its sickly broiling vapour, and at that very moment the words "NO U" drifted across the conference table. Unfortunately, in the Vl'Hurg tongue this was the most dreadful insult imaginable, and there was nothing for it but to wage terrible war for centuries. Eventually the error was detected, but over two hundred and fifty thousand worlds, their peoples and cultures perished in the holocaust.
You have destroyed most of a small galaxy. Please pick your words with greater care."