Undercover wear is clothing that is designed to be worn in order to conceal one's identity. The two most common types of undercover wear are jammies and pjs. Jammies, also known as pajamas, are loose-fitting garments usually made from cotton or silk. They typically consist of a top and bottom, and may include a hood or robe. Pjs, or pyjamas, are similar to jammies but are usually made from a heavier fabric such as flannel. They typically consist of a top and bottom, and may include a hood or robe. Both jammies and pjs are popular choices for undercover wear due to their comfort and ability to conceal one's identity.