Oral sex performed on the anus.
This is the technical term describing oral sex that pertains to the stimulation of one's anus, orally. More commonly referred to as 'rimming'.
This is the process of one using their mouth and tongue to stimulate their partner, through the anus, rectum.
It is important to practice safe sex procedures when dealing with high risk sex. Fecal matter can be dangerous, and caution should be taken when performing this sexual act. Hygiene is important.