Last minute shopping for costumes.
Halloween Eve is the name sometimes given to October 30, the day before Halloween, or the evening of that day. This is somewhat curious because the name "Halloween" is derived from the older form "All Hallows' Eve", meaning the day before All Hallows or All Saints' Day, therefore the "een" in "Halloween" itself means "Eve".
For many people, the day before Halloween is a time to set up their decorations, do some last minute costume preparations or buy candy for trick-or-treaters.
In some parts of the United States and Canada, and increasingly in Britain, the night before Halloween is Mischief Night, Devil's Night or Hell Night, when older children and teenagers commit foul play and mischief, such as "TPing" and egging, on their neighbors which can sometimes turn quite destructive.