It requires two players who understand this game, a leader and his accomplice. The accomplice leaves the room, while the leader and the rest remain inside. The leader asks the players what hour they will choose for the accomplice to guess. One will say: "Four o'clock." The assistant is called in and he questions the leader, saying: "Well, what time is it?" The leader answers thus: "Don't you know?"; next, "Doubtless, dancing time." The assistant immediately answers "Four o'clock," to the amazement of the company.

The key is that each hour, from 1 to 12 o'clock has been named according to the letters of the alphabet in rotation, from A to K, The leader, in answering, must be very careful to begin each answer with the letter indicating the chosen hour; thus in the above the assistant noticed that each answer began with "d," and "d" being the fourth letter, four o'clock was the time chosen. Only the exact hours must be chosen. As the different players think they understand the game, they may take the assistant's place, and many ludicrous mistakes will be the result until the game has been explained to all.