I've always known my asshole to be an erogenous zone (from playing with it myself) but just can't loosen up enough to let anyone go there. Must be some sort of toilet-training taboo hangup or some such. But not too long ago I attended a sex party that an out of town friend was hosting and after an all-night orgy he insisted I spend the night, since I had a long way to go, and drive home the next day. I accepted and when I awoke the next day I snuck through his bedroom to shower. Freshly showered I was passing by his bed when he reached out, grabbed my leg, pulled me towards him and started giving me head. I had cum three times during the previous twelve hours and knew full well I'd not reach orgasm again, but it felt good and soon I was hard and enjoying the blowjob.
He had me lay down on his bed with my legs over the edge and he on his knees continuing to suck my cock. Then he raised both my legs up high and began sucking on my balls while I took over working my cock with my hands. Taking over the ball massage with his own hands he began tonguing my perineum which felt ohhhhh sooooo good! Then very, very slowly, little by little he worked his tongue down to my ass crack. My first reaction was one of aversion and I nearly pulled away, but I thought what the hell loosen up and let it happen. My friend knew that I had that aversion to any kind of anal activity and he proceeded very slowly, gently and patiently. Eventually he was doing a full blown, aggressive job of tonguing my asshole and to my amazement I had an explosive orgasm. It was a totally memorable and enjoyable experience but I don't think I could repeat that experience unless it were with someone just as patient and understanding. As for returning the favor .... I'm still a long way from there. Maybe someday ...... ????