Tucking refers to the process of positioning the penis and testes in order to create an appearance of flatness in the genital region. Tucking is often done by transfeminine people as part of their gender expression, and some may desire bottom surgery in order to remove their external genitalia (normally in order to create a neovagina). Tucking can be held in place by medical tape, or through a tight pair of underwear. Specialised pairs of underwear for tucking are available, and is known as gaff underwear.