Started in North
London at crazy house parties. It is when
stuff is broken or moved around or just generally mucked up in
people'
s houses. It is not necessarily vandalism, just annoyances e.g. throwing an ironing board over a fence, or rearranging all the cupboards in the kitchen.
Also there is a varient called emotional mischief, whereby harsh rumours are spread about a particular person.
When mischief starts, the word "mischief" is chanted and the group partaking in the mischief charge around the house. It can also be done subtly.