Saturnalia

Saturnalia is a Roman festival which starts A.D. XVI Kalends Ian. and in the Republic lasted for 7 days. Saturnalia celebrated, the golden age of Saturn, when there was no war or want.

Merriment prevailed and social restrictions were turned upside down: a common practice was for the master to change place with his slaves. Public gambling was permitted.

A ritual took place at the Temple of Saturn, located in the Forum , where the wool wraps on the feet of the statue of Saturn were loosened.

The famous cry of the festival was 'Io Saturnalia.' "but suddenly shouted with one accord the well-known cry, "Io Saturnalia" (for at the festival of Saturn the slaves don their masters' dress and old festival)" Cassius Dio LX.19.3

From Lucian of Samosata:

"Secondly, during my week the serious is barred; no business allowed. Drinking and being drunk, noise and games and dice, appointing of kings and feasting of slaves, singing naked, clapping of tremulous hands, an occasional ducking of corked faces in icy water,--such are the functions over which I preside." Saturnalia, Book IV