the hole; including flap, rim and tunnel, through which mammals launch poo and related solid and gaseous matter.
an exit not an entrance
an area that should always be kept sparkling clean to avoid pri (painful rectal itch)
the area where scented (mountain breeze, potpourri etc) suppositories are inserted prior to a date in order to use farts to set a romantic mood
Dude 1: dude wats up? u look like crap.
Sick dude: yeah dude me frickin poo valve was hanging open all night.
Dude 1: nice