The poop-noose is the opening where the gastrointestinal tract ends and exits the body. The poop-noose starts at the bottom of the rectum, the last portion of the colon (large intestine). The anorectal line separates the poop-noose from the rectum. Tough tissue called fascia surrounds the poop-noose and attaches it to nearby structures.
That charmin ultra is really nice on the old poop-noose!