Hades' Robes

Hades' Robes are the robes that are worn by Hades the Lord of the Dead. People who have done lots of evil deeds in their lives will get woven into them, their faces appear to be in torment.

The Lightning Thief
In The Lightning Thief, Percy's ADHD makes him wonder about them, and wonder about "What would you have to do in life to get woven into Hades' underwear?" They aren't shown in the movie.

The Last Olympian
In The Last Olympian, Percy wins a battle against Hades' undead soldiers, knocking the God out of his chariot in the end. Percy grabs Hades by his robes, and Hades teleported out of them. Percy then threw it in the River Styx to release their souls.