Io Saturnalia!

Ancient Roman festival and holiday in honour of the god Saturn, held on 17-23 December of the Julian calendar. The holiday was celebrated with a sacrifice at the Temple of Saturn, in the Roman Forum, and a public banquet, followed by private gift-giving, continual partying, and a carnival atmosphere that overturned Roman social norms: gambling was permitted, and masters provided table service for their slaves as it was seen as a time of liberty for both slaves and freedmen alike.  A common custom was the election of a 'King of the Saturnalia' who gave orders to people, which were followed and presided over the merrymaking. The gifts exchanged were usually gag gifts or small figurines made of wax or pottery known as sigillaria.  

It held importance for some Romans, who saw it as a restoration of the ancient Golden Age, when the world was ruled by Saturn. In Roman mythology, Saturn was an agricultural deity who was said to have reigned over the world in the Golden Age, when humans enjoyed the spontaneous bounty of the earth without labour in a state of innocence.

The revelries of Saturnalia were supposed to reflect the conditions of the lost mythical age.