A loop of elastic & spandex fabric that wraps around one hip, between buttocks, and covers your junk. The loop can also be longer and go over one shoulder instead of the hip. Essentially a Half-Mankini (A Half Body Thong). A backless version of the Half Body Thong would be the Junk Sling; a pouch for one’s Junk and an elastic or cording drawstring over the neck.
Only a few guys can feel comfortable wearing a half thong to the beach.