|The following is based on Fallout Shelter and some details might contradict canon.|
Give the tricks, get the treats, and try not to go into sugar shock.”— In-game description
The ghost costume is an all white outfit with holes for the eyes and mouth. It provides the wearer an added +3 Agility and +2 Endurance.
If successful attempt disassembly of outfits you can get junk:
Ghost costume (1)
Free space in the storage room
Teddy bear (1)
The outfit was added with the 1.2 update, two weeks before the start of the winter 2015 Holiday season, with events like Halloween and Christmas coming up.
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