As I don't see a point in sharing my attention and focus to an audience, least of all, be watched like a zoo specimen about to procreate, I keep my encounters 1 on 1. I had a threesome experience which was very good (in my situation, it's reeeeally rare), but we all were directly active and I was focusing on one, then on another, back and forth.
The only time something happened that I was watched was accidental with a friend. It was extremely awkward for both of us, because he knew I hated that but couldn't do anything to leave that place at that moment (a downpour and he had lost his key to get back to his place, and we were in a single room hostel), and I knew that he would be uncomfortable with my size, twice his own. The chick was too busy to pay attention to anything else, but I had that buzz at the back of my head added to the excruciating attention I already had to pay not to hurt her while thrusting.
I'm very concerned with safety. This feeling stretches to many branches of my life and those around me. I'm the protector kind of guy. I don't hover, of course, but when I go with people I care to crowded areas, I simply enter a watchful-mode and get a little anxious, looking after all of them all the time, which is kind of ironic, considering most of them have high graduation on many self-defense fighting styles. On the other hand, I don't get like that when I'm alone in a crowd, because I can fend for myself and people usually give a wide berth, if I'm scowling or glowering. But I don't like to have my back, or my ass for that matter, exposed to a third party when I'm focusing on my business with a chick. They have no business there. And I can get cantankerous quite fast when my space is invaded.