New Year's Eve and Day are still celebrated more extensively, and vigorously, in Scotland than anywhere else in the world, necessitating a two-day public holiday to rest and recuperate afterwards.
Pitcairn's Criminal Trials in Scotland, records that as early as 1506, people were taking advantage of the holiday traditions for personal profit. That year several people were hanged as punishment for theft 'by way of mumming under silence of night'.
Mumming was, and still is in some places, a central feature of New Year's celebrations, and also other holidays throughout the year (more details at http://en.wikipedia.org/wiki/Mummer). People would dress up in fancy dress and masks to go about accompanied by music. In this disguise they were allowed freely to enter people's houses to perform their 'mummings' - dancing, singing and music. In the 18th century mumming became more closely associated with mummers' plays, rather than the more general entertainment that predominated before. A synonym for mumming is 'guising', which remains a popular practice in Scotland, although now associated almost exclusively with the costumes worn at Halloween.
Mumming also provided the perfect opportunity for theft, which if discovered resulted in the ultimate punishment. As Pitcairn's editor noted, another peculiar tradition - in this case embedded in common law - saw people executed for 'dishonourable' crimes such as theft or 'stoutreif', but allowed to make amends by paying compensation to the victim's family for acts such as murder and slaughter, especially if done in 'hot blood'.
Mumming survives in a number of places around the world. Most famously, Philidelphia's Mummer's Parade on New Year's Day, which has combined the British tradition with many other European customs to create a unique event.