The Hat on Cairo Station is an item that can be found at the beginning of Halo 2's Campaign level Cairo Station. The hat is an immovable object. At the beginning of Cairo Station, go to the crate to the right of the staircase. Sergeant Johnson's hat lies on top of the crate. If the crate is moved by grenades or melee attacks, the hat will float in midair and cannot be moved or picked up by the player. This item is not caused by a glitch, but actually because Bungie never intended for the player to attempt to interact with the hat, so such coding was not included.