The Mad Hatter is a character initially encountered at a tea party in Lewis Carroll's Alice's Adventures in Wonderland. Now you can become this legendary character in one of these mad hatter costumes. The chapter in which the mad hatter first appears is called "A Mad Tea Party", but is often refered to as "The Mad Hatter's Tea Party." The phrase "mad as a hatter" existed long before the character. The "10/6" on the Hatter's hat means ten shillings and six pence, the price of the hat in pre-decimalisation British money.