Mizzy Night means: A Liverpool-specific name for Mischief Night - the evening before a major holiday when kids traditionally go out and cause low-level chaos: knocking on doors, throwing eggs, tying gates, and. It is a dialectal or regional word and rarely appears in mainstream teen culture; usage usually points to a family, regional, or literary source rather than peer slang. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. As a place or proper-name reference it is purely descriptive.