The game that was called "Yes and No" in Scrooge's time is today more commonly called "Twenty Questions":
Where Scrooge's nephew had to think of something, and the rest must find out what; he only answering to their questions Yes or No as the case was.
In other words, Fred was thinking of something and the guests had to figure out what it was by asking only yes or no questions. As the guests ask their questions, a few things become clear. The subject in question was, in fact:
a live animal, rather a disagreeable animal, a savage animal, an animal that growled and grunted sometimes, and talked sometimes, and lived in London
Of course, the guests guess the gamut, including both a bear and a cat. (Ha!) Throughout the game Fred becomes increasingly tickled, often having to get up and stamp his foot. Finally, a female guest guesses the answer: Uncle Scrooge. Everyone laughs (except for the poor soul who insists that his question of "Is it a bear?" should have been answered in the affirmative). Fred finally ends the game with a jovial toast to Scrooge saying, "He has given us plenty of merriment, I am sure."
In Stave III of Charles Dickens’ A Christmas Carol, Ebenezer Scrooge is visited by the Ghost of Christmas Present. During their sojourn, the spirit takes Scrooge to the home of the old miser’s nephew, Fred, who is entertaining friends and clearly enjoying the camaraderie amid the spirit of the season. Scrooge observes the group playing a series of games, one of which is called “Yes and No,” and is described as follows:
“. . .Scrooge’s nephew had to think of something, and the rest must find out what; he only answering to their questions yes or no, as the case was. The brisk fire of questioning to which he was exposed, elicited from him that he was thinking of an animal, a live animal, rather a disagreeable animal, a savage animal, an animal that growled and grunted sometimes, and talked sometimes, and lived in London, and walked about the streets . . .”
In short, “Yes or No” was a version of today’s guessing games wherein the participants try and figure out the nature of the designated person’s thoughts. In Dickens’ story, however, Scrooge’s nephew, Fred, is thinking of the perpetually angry old man, and the clues to his identity lies in the description of a living but disagreeable animal – a description that understandably upsets the eavesdropping tyrant.