You can find A Barrel Costume in the Halloween Large Loot Bags that can be seen as loot on enemies during the RUST Halloween events.
When equipped, your player tag will disappear, and the Barrel will replace any equipment above your character’s waist.
Equipping a Barrel Costume will severely limit your field of vision to a small rectangle in the center of the screen. It will also reduce your movement speed by 30%.
It’s important to note that you cannot hold any weapons while wearing the costume. Also, your feet will stick out the bottom of the outfit unless you hold the crouch key.
Even if you are crouched, the Barrel Costume will sway slightly, giving your position away to more experienced players.