The reciever or anal sex who did not evacuate beforehand, and soils the "top" and/or the bedlinens along with themselves, such to an extent that it ruins sex and both partners need to shower. Also any ass that contains a bowel movement that is ready to be expelled.
Jeremy is a muddy bottom. Shiela and I did anal last night, she had a muddy bottom, sorry if I still smell.
by GayCO June 05, 2007