Not saying it never happens, but I seriously doubt that if it did occur, any average, regular old citizen of any country would be invited to view/participate in such an event.
I think, from what I have read and heard mind you, not first hand knowledgde, most porn stars view their job as just that: work. In fact, I really wish I could remember where I read this yesterday so I could post a link, but many porn stars work/have worked with others that they don't really even like all that much.
It's all about the money Old Guy. The closest you'll get to seeing something like this is going to be in a movie.