Some years ago, my steady girlfriend (I use the term advisedly as we were both in our late 40's), would ask me "will you kiss my anal lips, darling? Press your lips to mine and slip your tongue in me. Please!" It was a sort of stock phrase she used and I loved to hear it. I would kiss her there,lovingly, passionately, as if I were kissing her mouth and with my tongue exploring her she would often orgasm explosively. Then she would gently draw me up to her face and, opening her lips so invitingly, would draw my tongue inside, tasting herself from me. We both adored the act, the sensations and the little loving dialogues that acompanied them.
Gross? Perhaps to some. Another "gross" anal pleasure we enjoyed: I would press one of those chocolate finger biscuits into her anal passage then withdraw it with my teeth. Finally we would share it. For us it was a fantastic turn-on. For you ... who knows?