The No Game

The No Game is a party game with only one real rule. Sid Sackson wrote about it in A Gamut of Games, but it undoubtedly existed beforehand.

Play is as follows:

Locate a nice prize.
As everyone enters the party, pin a small ribbon on their clothes, one per person.
After everyone has arrived, gather them together and give a speech similar to the following:
- "The object of tonight's game is to collect the most ribbons. To collect ribbons, you must have an opponent say the word 'No' to you. Upon uttering that word, you may promptly collect every ribbon currently pinned on them; they are yours, at least until you say 'No.' Other words, phrases, and actions, like 'Nah,' 'Certainly not,' and a swift slap, are perfectly valid; only uttering the word 'No' causes a lack of ribbons. At [some time here], the person with the most ribbons wins the game, and receives a nice prize."
Play as the speech above states.

While simple in concept, it is surprisingly hard to remove the word 'No' from one's vocabulary; see lipograms for a literary equivalent.

Reference