Alice's Adventures in Wonderland, an 1865 novel written by Lewis Carroll, introduced multiple characters which have become cultural icons. Perhaps the most beloved scene is that of the mad tea party.
The party takes place on May 4th, so that is when we celebrate it!
Excerpted from the book:
"I've seen hatters before," she said to herself; "the March Hare will be much the most interesting, and perhaps as this is May it won't be raving mad--at least not so mad as it was in March."
The Hatter was the first to break the silence. "What day of the month is it?" he said, turning to Alice: he had taken his watch out of his pocket, and was looking at in uneasily, shaking it every now and then, and holding it to his ear.
Alice considered a little, and then said, "The fourth."
And there you have it - May 4th, Mad Tea Party Day!
"Clean cup! Move down!"