The Bilge Rat Shirt is a clothing item in Sea of Thieves. Trousers can be purchased from the General Clothing Shop on Outposts. Once purchased, the item will become available in the Clothing Chest near the General Clothing Shop or on the player's ship.
Rats were nesting in these, but after a quick wipe over you'd hardly tell.
How to Unlock
This item is already available at the beginning of a new game.