Anilingus (oral on anus)
Also called rimming. One partner uses tongue and mouth to stimulate around and just inside the other’s anus. This is very intimate and taboo for some, but can produce intense pleasure because of the concentration of nerves. Hygiene is crucial (washing beforehand, maybe using dental dams if concerned). It can be done with the receiver on their back with legs up or on all fours, etc. Go slow – licking around the rim, maybe gentle probing. The combination of psychological naughtiness and physical sensation can be a huge turn-on for some. Only do if both are completely comfortable with it.