You just need to start telling your man what you enjoy about him and what he is doing, “i love how big you feel” or “keep hitting that spot” or “keep going, harder” or “you feel so good inside me. Not necessarily giving, though i have girlfriends who enjoy receiving it so i sometimes do it, but i have a prostate and man, prostate stimulation feels. I once had a gf who was down for it any time, and we both got bored of it really quickly tbh. The anus is a receptive organ, but it needs to be courted with care. Unlike the vagina, the anus doesn’t create its own lubrication during arousal.
As i slowly fuck her – gradually increasing the tempo – she alternates between those moans and requests to fuck her deeper and / or harder. But i soon realized poop isn’t a big deal at all, even if you do get a little on you.