Hmm, well my most public was not too long ago. I was with a friend of mine, who's rather taken it upon himself to be my "gay tour guide". We had been talking about public sex, after having just seen someone exposing themselves to someone else on the sidewalk. Later, we were in a subterranean parking structure, and while walking toward the stairs up to the street, he told me the jeans I was wearing made my ass look good, and how good I smelled. Then when we were in the stairwell, almost up to the street level, he grabbed the back of my jeans, asked where I thought I was going, reached around and undid them. I asked what he was doing, but fell forward up the stairs when he pushed me. Before I could say or do anything else, I'm standing with my jeans around my legs, binding me, my hands on the stairs a few rungs higher, trying to figure out what's going on, when he suddenly sinks his face into my ass and starts rimming me deep. It was at night, so there weren't a lot of people, but when there were, they were walking by about 5-10 feet above me. Then, he reached around me and started jacking off my cock until I came all over the stairs. He just laughed and said, "Better get your pants back on. That's all you get, for right now. You're lucky I didn't have a rubber with me, or all those people that walked by would've seen you getting SO fucked."