A person who enjoys bright neon colored clothing, loud electronic music, lasers lights, glow-sticks, fractals, and anything fuzzy.
Raver gnomes are occasionally known to make certain items disappear, only to make them reappear(usually drug related items) at a later date, in greater or lesser quantities.
Raver Gnome: Creature Type, Raging Raver
The three people who show up at your house at the middle of the night and are very happy, dressed like Santa's elves from the 60's.