Pornosex is having sex, with at least one other person (or, I guess at least one animal, if you're into that), while you watch porn.
My girlfriend broke up with me, and is now banging my brother. Luckily, my girlfriend (and my brother) are both HOT, and she still sends me video.
So my new girlfriend and I have "Pornosex". We have sex, with each other, while watching the video. I do have to take special precautions, while watching my ex-girlfriend's video, however, to prevent sibsex. When I watch I close one eye, and only look at the 1/2 of the screen that has my ex-girlfriend on it. My girlfriend, even though she wouldn't get sibsex, of course, doesn't want to watch my ex, so she closes her other eye and watches the other 1/2 of the screen with my brother on it. Works great for us!!!