This situation is real. My girlfriend and I were in a shop where they sell sex toys, movies, etc, and there is a couples room in the back where they have leather couches and erotic movies playing. After being in the couples room we wound up having sex on a leather couch. At one point I was fully naked on the couch and sitting up while my g/f was on top. Is it possible to have caught an std anally from being naked on that leather couch if there had been previous sex/fluids there?