From the online hit "Dragonball Z Abridged" created by Team Four Star, Ghost Nappa is the awesomely hilarious poltergeist Nappa becomes after Vegeta kills him in Episode 9.
Nappa was quickly established as everyone's favorite character, and to keep him in the show, Team Four Star invented Ghost Nappa. Those clever bastards.
"When there's something strange, in the neighborhood, guess who it is? GHOST NAPPA!"