The Sneaky Parasol is a special parasol Princess Peach can use to turn herself into anyone in Paper Mario. After Mario and company defeated Lava Piranha and rescued the Star Spirit Misstar, Peach had to participate in a Quiz Show Bowser's guards were holding to win this item.
During Peach's event, after Mario and his teammates defeat Huff N. Puff and rescue the Star Spirit Klevar, she uses this item to turn herself into one of Bowser's guards and wander around her castle without getting caught. To use the parasol, Peach must sneak behind a Koopatrol, Clubba, or Hammer Brother and press B to transform. To change back into Peach, press B again.