I'll go with one of the first scenes that I ever watched, back when I was 15 or so.. a friend lended me a tape with a whole bunch of vids on it but the tape didn't have titles so I didn't know what the hell I was about to watch. It turned out that one of the movies on there was taboo and I had no idea what the theme for the movie was prior to this.. anyways, the scene where the dude is sleeping and his mother walks in, notices a hard-on and begins sucking him off was bad enough.. I believed that was followed by fucking. Later in the film, the mother tries to apologize for what happened the night before but the kid won't have any of that and says that he wants it to happen again then starts making out with her, removing her shirt, and so on..

Nothing quite as disgusting comes to memory but maybe since this was one of the first scenes I've seen and I had no idea that it was an incest themed film. I remember rewinding the tape to check and see if I had mistaken the woman as the guy's mother because I was in such disbelief, of course it's just a vid and they aren't really mother and son.. it's just the same as a cannabal film in the sense that you know it's fake but you still can be repulsed by the idea of that really happening.