Rimming or anilingus involves using the tongue to explore someone's arse. It can be a form of play by itself or a great technique used as a part of foreplay and to get the hole relaxed before introducing fingers, toys or cocks.
Feltching is sucking semen out of someone’s arse. If you have mouth ulcers or sores, small cuts, gingivitis or gum disease, there is a possibility of getting HIV if you have cum from an HIV positive partner in your mouth.
Usually, for feltching to happen unprotected anal sex and cumming inside someone has to occur. Anal sex without condoms with guys of unknown HIV status carries the highest risk with regard to getting or passing on HIV. However, in some cases sperm is collected in a condom or in the mouth of a willing participant to then reintroduce it into someone’s arse to play. This exchange of body fluids has a similar risk of infection as unprotected anal intercourse. For more about minimising risks of getting or passing HIV go to Fucking.