Deathday Party
Celebrating Nearly Headless Nick's 500th Deathday
Jet-black tapers with blue flames
Appalling food
Icy blue spotlight on the podium
Chandelier with blue-flamed candles overhead
Held in one of the roomier dungeons
Orchestra of 30 musical saws (quavering, dreadful music)

Special guests: Harry, Ron, and Hermione
Headless Hunt - a dozen horses with headless riders
Head Hockey

Attended by hundreds of ghosts, including all the Hogwarts ghosts and:

Sir Patrick Delany-Podmore - leader of the Headless Hunt, with a group of his huntsmen
Group of gloomy nuns
Ragged man wearing chains