A rimjob is the act of licking, kissing or sucking another's anal sphincter in order to cause sexual pleasure.
Although that definition may meet with gags from some, from others it elicits the raised eyebrows, so to speak, of sensory adventure. And rightly so. Besides being a poop-chute, the anus is a neglected vibrant network of nerve endings, the forgotten playmate to Brother Penis and Sister Vagina, Cousins Mouth and Tongue.
It is with these last two relations that this lovely act is ultimately concerned. Playful and open-minded lovers, while administering oral affections on a partner's happy spots often receive amorous inspiration and allow their lips to wander ever-delightfully southward. It could be argued that the sense of intimacy and surrender is even heightened during a well-performed rimjob.
Of course, performance depends on practice so grab a friendly partner, pay attention, and expand your lovemaking repertoire.