Find Woody the ghoul for Percy. Try the Den.
Show! Me! The! Mummy!
You woke up Woody the ghoul and freed him from indentured mummy-tude.”— Post completion message
You receive this quest in Gecko, at the Survival/Gear shop at the Gecko Junkyard. Talk to Percy, and he'll tell you how he's worried about his friend Woody, who has disappeared. As the game recommends, go to the Den.
At the Den West Side, go to the guy that supposedly has an ancient Egyptian mummy, which is south, in the haunted house. Talk to him and pay $25 to have him show you the "mummy". You will recognize that the mummy is, in fact, a ghoul wrapped in toilet paper. Wake Woody up and tell him to run.