Twelfth-day — Chambers's Encyclopaedia

Twelfth-day, the twelfth day after Christmas, the feast of the Epiphany (q.v.), was once a time of great popular festivities, originally designed to honour the Three Kings (see MAGI). One of the chief features was the choosing of a king of the feast by means of a bean hidden in the Twelfth Cake. When on the eve of the feast this cake was cut up and distributed, the person in whose portion the bean was found was king—hence called Bean-king. This choosing of a king by means of a bean was in use at some other festivals also.