When the gang decided to investigate the light house, Fred notes that the trap door to the light platform is small, and that they'll have to go up one-by-one. Daphne volunteers to go up first, and is grabbed by the ghost, who then puts a barrel on top of the door. When Fred manages to open the door, he, Shaggy, Scooby, and Velma go though the opening together, even though it was too small a minute before,
Despite Daphne's apparent love of the onesie Verona gave her, she for some reason never puts it on. Presumably, so it could save her life later on.